Learn Hardcore Greek: Στο μάθημα ελληνικών μαθαίνουμε όχι μόνο λέξεις αλλά και εκφράσεις που χρησιμοποιούν οι Έλληνες κάθε μέρα. - In the Greek lesson we learn not only words but also expressions that Greeks use every day.

Ελληνικά is the adverb/adverbial form meaning “Greek (language)” in general, while ελληνικών here is a genitive plural form of the adjective ελληνικός, -ή, -ό used like a noun: “(of) Greek”.

μάθημα ελληνικών literally = “lesson of Greek”
ελληνικών is genitive plural neuter (matching the understood noun “words / language”)

In Greek, when one noun is “of” another noun (a lesson of Greek, a book of history, a glass of water), the second noun typically goes into the genitive:

μάθημα ελληνικών = Greek lesson / Greek class
βιβλίο ιστορίας = history book
ποτήρι νερού = glass of water

Μάθημα ελληνικά is not grammatical; you need the genitive to show the relationship “lesson of X”.

Why is there no article before ελληνικών? Why not μάθημα των ελληνικών?

Both are possible, but they’re not used in the same way:

το μάθημα ελληνικών
- Very common and smooth.
- Functions like a set phrase: "Greek class / Greek lesson".
- ελληνικών functions almost like an adjective defining the type of lesson.
το μάθημα των ελληνικών
- Literally “the lesson of the Greek [language]”.
- Grammatically correct, but sounds heavier/more formal or specific, and less like the usual name of a school subject.
- More likely in contexts like talking about a particular curriculum:
  - Το μάθημα των ελληνικών στο σχολείο είναι δύσκολο.

For naming school subjects, Greek often drops the article in these genitive constructions:

μάθημα μαθηματικών = math class
μάθημα αγγλικών = English class
μάθημα ελληνικών = Greek class

What does μαθαίνουμε tell us exactly? Why is there no word for “we”?

Μαθαίνουμε is the 1st person plural form of the verb μαθαίνω (to learn):

μαθαίνω = I learn
μαθαίνεις = you learn (singular)
μαθαίνει = he/she/it learns
μαθαίνουμε = we learn
μαθαίνετε = you learn (plural/formal)
μαθαίνουν(ε) = they learn

Greek verb endings encode the subject, so the pronoun (εμείς = we) is usually dropped unless you want to emphasize it:

(Εμείς) μαθαίνουμε όχι μόνο λέξεις…
We (and not others) learn not only words…

In normal, neutral sentences, you just say μαθαίνουμε and it already means “we learn / we are learning”.

How does the structure όχι μόνο … αλλά και … work? Do I always need the και?

όχι μόνο … αλλά (και) … means “not only … but (also) …”.

In detail:

όχι μόνο λέξεις = not only words
αλλά και εκφράσεις = but also expressions

General pattern:

όχι μόνο X, αλλά (και) Y
Example:
- Δεν μου αρέσει μόνο ο καφές, αλλά και το τσάι.
- I don’t like only coffee, but also tea.

About και:

Including και after αλλά is very common and very natural:
- όχι μόνο Χ, αλλά και Υ
You can sometimes drop και, especially in more formal or literary style, but everyday language usually keeps it.

So the sentence uses a standard, very frequent pattern that you’ll see all the time in Greek.

Why are λέξεις and εκφράσεις in this form? What case and number are they?

Both λέξεις and εκφράσεις are:

feminine plural, accusative

λέξη (word) → plural nominative/accusative: λέξεις
έκφραση (expression) → plural nominative/accusative: εκφράσεις

They are the direct objects of μαθαίνουμε (“we learn what?”):

μαθαίνουμε λέξεις → we learn words
μαθαίνουμε εκφράσεις → we learn expressions

In Greek, the accusative is typically used for the direct object of the verb. In the plural of these feminine nouns, the nominative and accusative look the same, so context (their role in the sentence) tells you they are objects.

Why is there no article (no “the”) before λέξεις and εκφράσεις?

In Greek, when speaking generally about things in the plural, you can omit the article much like in English:

μαθαίνουμε λέξεις = we learn words (in general)
μαθαίνουμε εκφράσεις = we learn expressions (in general)

Compare:

Οι λέξεις αυτές είναι δύσκολες.
- The words are difficult. (here you mean specific words → article appears)
Στο μάθημα ελληνικών μαθαίνουμε λέξεις.
- We learn words (as a kind of thing we study) → generic, no article needed.

So here the speaker is not talking about some specific set of words and expressions already known; it’s about the type of content you learn in class.

What is the function of που in εκφράσεις που χρησιμοποιούν οι Έλληνες? Is it like “that” or “which”?

Yes. Που is a very common relative pronoun in modern Greek, roughly meaning “that / which / who” in English.

εκφράσεις που χρησιμοποιούν οι Έλληνες
= expressions that Greeks use

It introduces a relative clause that describes εκφράσεις:

εκφράσεις → main noun
που χρησιμοποιούν οι Έλληνες κάθε μέρα → clause giving more information about those expressions

Important points:

Modern Greek uses που for most everyday relative clauses, regardless of whether English would say “that”, “which”, or “who”.
Older or more formal Greek may use ο οποίος, η οποία, το οποίο, but που is much more frequent in speech.

In που χρησιμοποιούν οι Έλληνες, why does οι Έλληνες come after the verb? Can you put it before?

Greek word order is flexible, because the roles of words are mostly shown by endings (cases), not by position.

Current order:

που χρησιμοποιούν οι Έλληνες
literally: that use the Greeks → “that Greeks use”

Here, οι Έλληνες is clearly the subject because of:

the article οι (nominative plural)
the ending -ες on Έλληνες (nominative plural masculine)

You could also say:

που οι Έλληνες χρησιμοποιούν κάθε μέρα

Both are grammatically correct. The original order (χρησιμοποιούν οι Έλληνες) is very natural and common in Greek; putting the subject after the verb is not unusual.

Why is it οι Έλληνες and not τους Έλληνες?

Because here, Έλληνες is the subject of the verb χρησιμοποιούν (they use). Subjects appear in the nominative case:

οι Έλληνες (nominative plural) = Greeks (as the subject)
τους Έλληνες (accusative plural) = Greeks (as object: someone does something to them)

In our sentence:

εκφράσεις που χρησιμοποιούν οι Έλληνες
- expressions that Greeks use (Greeks = subject → nominative: οι Έλληνες)

If Greeks were the object, then you would need τους Έλληνες, but here they are the ones performing the action.

What tense is χρησιμοποιούν? Does it mean “use” or “are using”?

Χρησιμοποιούν is in the present indicative:

αυτοί χρησιμοποιούν = they use / they are using

Modern Greek present tense usually covers both simple present and present continuous in English. Context decides which English form you choose to translate:

Οι άνθρωποι τρώνε ψωμί.
- People eat bread. (general fact)
Τώρα τρώμε.
- We are eating now. (right now)

In this sentence, χρησιμοποιούν is describing a habitual action (what Greeks generally do every day), so English uses simple present:

εκφράσεις που χρησιμοποιούν οι Έλληνες κάθε μέρα
= expressions that Greeks use every day

What does κάθε μέρα mean exactly? Is it different from καθημερινά or ημέρα?

κάθε μέρα literally = “every day”.

κάθε = every / each
μέρα = day (colloquial form of ημέρα)

Alternative forms/phrases:

κάθε ημέρα → more formal/spelled-out version of “every day”; meaning is the same.
καθημερινά = every day / daily (adverb)
- Παίρνω καφέ καθημερινά. = I get coffee every day / daily.

In this sentence, κάθε μέρα is the most natural everyday choice:

εκφράσεις που χρησιμοποιούν οι Έλληνες κάθε μέρα
= expressions that Greeks use every day

Could we change the word order to Στο μάθημα ελληνικών μαθαίνουμε όχι μόνο λέξεις αλλά και εκφράσεις κάθε μέρα που χρησιμοποιούν οι Έλληνες?

You could, but it becomes confusing or awkward. In Greek, as in English, word order also affects clarity, especially with clauses like που χρησιμοποιούν οι Έλληνες.

Original:

εκφράσεις που χρησιμοποιούν οι Έλληνες κάθε μέρα
→ clear: expressions that Greeks use every day.

Your re-ordered version:

εκφράσεις κάθε μέρα που χρησιμοποιούν οι Έλληνες
→ this risks sounding like: every day expressions that Greeks use or attaching κάθε μέρα to μαθαίνουμε instead.

Better alternate word orders that keep the meaning clear:

Στο μάθημα ελληνικών μαθαίνουμε, κάθε μέρα, όχι μόνο λέξεις αλλά και εκφράσεις που χρησιμοποιούν οι Έλληνες.
Στο μάθημα ελληνικών μαθαίνουμε όχι μόνο λέξεις αλλά και εκφράσεις που οι Έλληνες χρησιμοποιούν κάθε μέρα.

Greek is flexible, but you still try to keep που + clause close to the noun it describes (εκφράσεις) to avoid ambiguity.

What’s the difference between Έλληνες and ελληνικά / ελληνικών? Why is one capitalized and the others not?

Έλληνες (with capital Ε) = Greeks (people); a proper noun / demonym.
ελληνικά = Greek (language), “Greek” as a subject; written with small ε.
ελληνικών = genitive plural of the adjective ελληνικός used as a noun, meaning “of Greek (language)”. Also not capitalized.

Capitalization rules:

Nationalities/language as people → capitalized:
- οι Έλληνες, οι Γάλλοι, οι Ιταλοί
Adjectives and words for languages in general → not capitalized:
- τα ελληνικά, τα αγγλικά, η γαλλική γλώσσα

So in this sentence, οι Έλληνες is capitalized because it refers to the Greek people; ελληνικών is lower-case because it is about the Greek language / Greek as a subject, not a proper name.