Learn Hardcore Greek: Αυτός ο μήνας είναι ήσυχος στη δουλειά.

Αυτός ο μήνας literally means this the month, but together it just means this month.
Leaving out the article (Αυτός μήνας) sounds wrong or very unnatural in modern Greek.

So: demonstrative (Αυτός) + article (ο) + noun (μήνας) is the normal pattern:
Αυτός ο μήνας, αυτή η μέρα, αυτό το παιδί.

Why is it Αυτός and not Αυτό or Αυτή?

The demonstrative must agree with the noun in gender, number, and case.

μήνας is masculine, singular, nominative.
So you need the masculine nominative singular form: αυτός.

Forms of “this” in the nominative singular:

Masculine: αυτός (for words like ο μήνας, ο άνθρωπος)
Feminine: αυτή (for words like η μέρα, η δουλειά)
Neuter: αυτό (for words like το παιδί, το βιβλίο)

So: Αυτός ο μήνας = this month (masc.)
If the noun were feminine, e.g. η εβδομάδα (the week), you’d say Αυτή η εβδομάδα.

Why is it ο μήνας and not η μήνας or το μήνας?

Greek nouns have grammatical gender. Μήνας (month) is masculine, so it takes the masculine article ο.

ο μήνας – the month
του μήνα – of the month
τον μήνα – (I see) the month

Feminine would take η, neuter would take το, but μήνας is simply a masculine word, so ο is the correct article here.

Why is μήνας in this form? Shouldn’t it be μήνα like “τον μήνα”?

Μήνας is in the nominative case because it is the subject of the sentence:

Αυτός ο μήνας (subject) είναι … (verb)

When μήνας is the object or part of a time expression with no preposition, you often see the accusative:

Βλέπω τον μήνα. – I see the month.
Θα δουλέψω όλον τον μήνα. – I’ll work all month.

Here, we’re saying “This month is quiet …” so month is the subject → nominative μήνας.

Could we say Αυτόν τον μήνα είναι ήσυχα στη δουλειά instead? What’s the difference?

Yes, that’s also correct, and actually very natural:

Αυτόν τον μήνα είναι ήσυχα στη δουλειά.
This month (during this month), it is quiet at work.

Differences:

Αυτός ο μήνας είναι ήσυχος στη δουλειά.
Grammatically, “This month” is the subject; you are describing the month itself as quiet (at work).
Αυτόν τον μήνα είναι ήσυχα στη δουλειά.
Here αυτόν τον μήνα is a time expression (“this month”), and the real subject is implicit “it” → It is quiet at work this month.

Both are correct; (2) is probably what you’ll hear more in everyday speech.

Why is it είναι and not just Αυτός ο μήνας ήσυχος στη δουλειά?

In Greek you normally must use the verb είμαι (“to be”) to link a subject and an adjective:

Αυτός ο μήνας είναι ήσυχος. – This month is quiet.
Η δουλειά είναι δύσκολη. – Work is difficult.

Leaving out είναι here (Αυτός ο μήνας ήσυχος στη δουλειά) sounds incomplete or ungrammatical in standard modern Greek. Unlike some languages, Greek doesn’t normally drop “to be” in the present tense in this kind of sentence.

Why is the adjective ήσυχος in the masculine form? Could it be ήσυχη or ήσυχο?

The adjective ήσυχος must agree with the noun μήνας in gender, number, and case.

μήνας: masculine, singular, nominative
So the adjective must also be: masculine, singular, nominative → ήσυχος

Main forms of the adjective:

Masculine: ήσυχος (ο ήσυχος μήνας)
Feminine: ήσυχη (η ήσυχη μέρα)
Neuter: ήσυχο (το ήσυχο βράδυ)

If the subject were feminine, you’d say:
Αυτή η εβδομάδα είναι ήσυχη. – This week is quiet.
With a neuter:
Αυτό το βράδυ είναι ήσυχο. – This evening is quiet.

What is the difference between ήσυχος and ήσυχα? Could I say Είναι ήσυχα στη δουλειά?

Yes, you can say Είναι ήσυχα στη δουλειά. That is a very common sentence and means:

Είναι ήσυχα στη δουλειά. – It is quiet at work.

Here ήσυχα is the neuter plural form of the adjective, used adverbially, like “things are quiet”.

In your original sentence:

Αυτός ο μήνας είναι ήσυχος στη δουλειά.

you are making “this month” the subject and describing it with the masculine adjective ήσυχος.

Both are correct but structured differently:

Αυτός ο μήνας είναι ήσυχος στη δουλειά. – This month is quiet (at work).
Είναι ήσυχα στη δουλειά αυτόν τον μήνα. – It is quiet at work this month.

What exactly does στη δουλειά mean, and how is it formed?

Στη δουλειά means “at work” or “in/at the job”.

It’s formed like this:

σε = in / at / to
τη = the (feminine, singular, accusative)
δουλειά = work, job (feminine noun)

σε + τη → στη

So literally: στη δουλειά = in/at the work.
Greek usually uses the article, even when English does not:
English: at work → Greek: στη δουλειά (literally “at the work”).

Why is it τη δουλειά in στη δουλειά? Why feminine?

The noun δουλειά (work, job) is feminine, so its article is η (nominative), and τη (accusative).

Nominative: η δουλειά – the work / the job
Accusative: τη δουλειά – (I see) the work / to the work

The preposition σε (“in, at, to”) requires the accusative case, so you get σε τη δουλειά, which contracts to στη δουλειά.

Because δουλειά is feminine, you don’t use στο (masc./neuter) but στη (fem.) instead.

In writing, should it be στη δουλειά or στην δουλειά?

Both forms appear, but the more standard modern spelling here is:

στη δουλειά

The ν at the end of στη(ν) is usually kept only before:

κ, π, τ, ξ, ψ, γκ, μπ, ντ, τσ, τζ
and often before vowels.

Since δουλειά starts with δ, you can (and normally do) drop the final ν:

στη δουλειά (most common in standard writing)
στην δουλειά (also seen, not “wrong”, but less standard according to modern rules)

How do you pronounce the whole sentence?

In IPA, a common modern Greek pronunciation is:

Αυτός ο μήνας είναι ήσυχος στη δουλειά.
/afˈtos o ˈminas ˈine ˈisixos sti ðulˈʝa/

Some key points:

Αυτός → /afˈtos/
- αυ is pronounced [af] here because it’s before a voiceless consonant (τ).
μήνας → /ˈminas/ (stress on μή)
είναι → /ˈine/ (the final -αι sounds like -e)
ήσυχος → /ˈisixos/ (stress on ή, χ = a harsh h sound)
δουλειά → /ðulˈʝa/
- δ = “th” in this
- ου = “oo” in food
- ει = “i” in machine
- γ + ι (in λειά) gives the soft /ʝ/ sound.

The main stress is on: Αυτός, μήνας, είναι, ήσυχος, δουλειά – each word has one stressed syllable marked with the accent (´) in writing.