Learn Hardcore Greek: Αυτό το κείμενο είναι λίγο δύσκολο για εμένα σήμερα. - This text is a bit difficult for me today.

Αυτό το κείμενο literally is this the text, but in Greek that’s the standard, natural way to say this text.
Leaving out the article (Αυτό κείμενο) sounds wrong or very unnatural in modern Greek in almost all everyday contexts.

What gender and case is κείμενο, and how do Αυτό and το agree with it?

κείμενο is neuter, singular, nominative.
- It’s the subject of the sentence: Αυτό το κείμενο = This text.

Greek requires agreement:

Αυτό is neuter singular nominative (the demonstrative).
το is neuter singular nominative (the definite article).
κείμενο is neuter singular nominative (the noun).

All three match in gender (neuter), number (singular), and case (nominative) because they refer to the same thing and form the subject.

Could I also say Το κείμενο αυτό instead of Αυτό το κείμενο? Is there any difference?

Yes, both are grammatically correct:

Αυτό το κείμενο είναι λίγο δύσκολο…
Το κείμενο αυτό είναι λίγο δύσκολο…

Both mean “this text is a little difficult…”.

The difference is mainly one of style and emphasis:

Αυτό το κείμενο is the most neutral, common order.
Το κείμενο αυτό can sound a bit more marked, as if you’re contrasting or specifying:
- like English: “this particular text” (as opposed to some other text).

In everyday speech, Αυτό το κείμενο is more frequent, but Το κείμενο αυτό is perfectly natural.

Why is είναι used here, and how would this verb change with different subjects?

είναι is the 3rd person form of the verb είμαι = to be.

Present tense of είμαι:

(εγώ) είμαι = I am
(εσύ) είσαι = you are (singular)
(αυτός/αυτή/αυτό) είναι = he / she / it is
(εμείς) είμαστε = we are
(εσείς) είστε = you are (plural / polite)
(αυτοί/αυτές/αυτά) είναι = they are

In Αυτό το κείμενο είναι λίγο δύσκολο…, the subject (Αυτό το κείμενο) is 3rd person singular, so we use είναι.

Notice: in Greek, 3rd person singular and plural are both “είναι”; context tells you if it means “is” or “are”.

What exactly does λίγο mean here? Is it an adjective or an adverb?

In this sentence, λίγο is an adverb modifying the adjective δύσκολο:

λίγο δύσκολο ≈ a little difficult, a bit difficult, somewhat difficult

So it’s softening the adjective, not describing a noun.

Compare:

λίγο νερό = a little water (here λίγο is more like a quantifier before a noun)
είναι λίγο δύσκολο = it is a bit difficult (here λίγο is an adverb modifying the adjective)

You can often move it slightly:

είναι λίγο δύσκολο (most natural)
είναι δύσκολο λίγο (possible, but less common; can sound a bit marked or poetic, depending on context)

Why is δύσκολο in the neuter form and not δύσκολη or δύσκολος?

Adjectives in Greek must agree with the noun they describe in gender, number, and case.

The noun κείμενο is neuter, singular, nominative.
Therefore, the adjective must also be neuter singular nominative: δύσκολο.

If the noun were different, the adjective would change:

Ο διάλογος είναι δύσκολος. (masc) = The dialogue is difficult.
Η άσκηση είναι δύσκολη. (fem) = The exercise is difficult.
Το κείμενο είναι δύσκολο. (neut) = The text is difficult.

So δύσκολο matches κείμενο in form.

Could I say Αυτό το κείμενο είναι λίγο δύσκολο κείμενο?

That sounds wrong in Greek.

You basically have two choices:

Predicate adjective (as in the original):
- Αυτό το κείμενο είναι λίγο δύσκολο.
  This text is a little difficult.
Adjective directly before the noun:
- Αυτό είναι ένα λίγο δύσκολο κείμενο.
  This is a somewhat difficult text.

But you don’t normally repeat the noun after είναι with the same noun and an adjective:

✗ Αυτό το κείμενο είναι λίγο δύσκολο κείμενο. → unnatural / wrong

Either you:

keep δύσκολο as a predicate adjective (no noun after it), or
move the adjective in front of the noun and use an article (ένα δύσκολο κείμενο).

What does για εμένα literally mean, and why is εμένα in that form?

Literally:

για = for
εμένα = me (strong/emphatic form of the 1st person singular pronoun)

So για εμένα = for me.

About εμένα:

The basic subject form is εγώ = I.
The object / strong form is εμένα (or less formally μένα) = me.
After most prepositions (like για), Greek uses this strong form:
- για εμένα / για μένα = for me
- σε εμένα / σε μένα = to me
- χωρίς εμένα = without me

Using εμένα here is normal; it can carry a nuance of “for me personally”.

What’s the difference between για εμένα, για μένα, and using forms like με or μου here?

για εμένα and για μένα
- Both mean for me.
- εμένα is slightly more formal or more clearly emphatic.
- μένα is the more everyday colloquial form.
- In speech, για μένα is extremely common.
με and μου are weak (clitic) pronouns and cannot replace για εμένα here:
- με = me (direct object):
  - Με βοηθάει. = He/she helps me.
- μου = my / to me (genitive):
  - Είναι δύσκολο για τον αδερφό μου. = It is difficult for my brother.

In για εμένα σήμερα, you must use a strong pronoun after για, so:

για εμένα or για μένα, not για με or για μου.

Could I leave out για and just say είναι λίγο δύσκολο εμένα?

No, that would be incorrect.

Greek needs the preposition για to express “for (someone)” in this sense:

δύσκολο για εμένα = difficult for me
εύκολο για σένα = easy for you

Without για, εμένα would just be hanging there without the correct grammatical link, and the sentence would not be grammatical.

So you must say:

…είναι λίγο δύσκολο για εμένα.
or
…είναι λίγο δύσκολο για μένα.

Why is για used instead of σε (like σε μένα) to mean “for me”?

It’s mostly a matter of which preposition the adjective normally takes.

For difficulty/ease, the common pattern is:

δύσκολος για κάποιον = difficult for someone
εύκολος για κάποιον = easy for someone

So:

είναι δύσκολο για εμένα = it is difficult for me.

σε is often used with verbs or adjectives that mean to someone or towards someone (direction or target), but with difficult / easy (for someone) the natural preposition is για, not σε.

✗ δύσκολο σε εμένα would sound wrong or at least very odd.

Where can σήμερα go in the sentence, and does moving it change the meaning?

σήμερα = today is an adverb of time. It’s quite flexible:

All of these are grammatical and mean essentially the same thing:

Αυτό το κείμενο είναι λίγο δύσκολο για εμένα σήμερα.
Αυτό το κείμενο είναι σήμερα λίγο δύσκολο για εμένα.
Σήμερα αυτό το κείμενο είναι λίγο δύσκολο για εμένα.

Differences are mainly emphasis / focus:

Version 1 (original) is the most neutral: you state the situation, then add “today” at the end”.
Version 3 (starting with Σήμερα) emphasizes today: Today, this text is a bit difficult for me (maybe on other days it isn’t).

Greek word order is fairly flexible, but the default, most natural place for σήμερα here is at or near the end, as in the original sentence.