Αυτή η συλλαβή είναι δύσκολη για μένα όταν μιλάω γρήγορα.

In Modern Greek, a demonstrative like αυτός / αυτή / αυτό (this) is very often used together with the definite article:

• αυτή η συλλαβή = this syllable
• literally: this the syllable

This is normal Greek, not redundant. Both words must agree with the noun in gender, number, and case.

Here, συλλαβή is:

• feminine
• singular
• nominative

So Greek uses:

• αυτή = feminine singular nominative demonstrative
• η = feminine singular nominative article

συλλαβή means syllable, and it is a feminine noun in Greek.

That matters because the other words around it have to match it:

• αυτή → feminine
• η → feminine
• δύσκολη → feminine

So the sentence is built around the fact that συλλαβή is feminine singular.

Because adjectives in Greek agree with the noun they describe.

The noun here is η συλλαβή, which is feminine singular, so the adjective must also be feminine singular:

• masculine: δύσκολος
• feminine: δύσκολη
• neuter: δύσκολο

So:

• Η συλλαβή είναι δύσκολη = The syllable is difficult

If the noun were neuter, you would use δύσκολο instead.

Yes. για μένα literally means for me, and in Greek it is a very natural way to express difficult for me, easy for me, important to me, and so on.

So:

• είναι δύσκολη για μένα = it is difficult for me

This is one common Greek pattern:

• εύκολο για μένα = easy for me
• δύσκολο για μένα = difficult for me

English sometimes uses for me, sometimes just I find it difficult, but Greek often keeps the για + pronoun structure.

Because after the preposition για (for), Greek uses the pronoun form μένα, not the subject form εγώ.

Compare:

• εγώ μιλάω = I speak
  (εγώ = subject form)

• για μένα = for me
  (μένα = oblique form used after prepositions)

You may also see για εμένα, which is a fuller version.
Both για μένα and για εμένα are correct.

Both mean me in this kind of structure.

• για μένα = very common, everyday
• για εμένα = also correct, sometimes a bit fuller or more emphatic

In many situations, the shorter form is the one learners will hear most often.

So in this sentence, για μένα is completely natural.

Greek often uses the present tense after όταν when talking about something that happens generally, habitually, or whenever a situation occurs.

Here the meaning is something like:

• when I speak quickly
• whenever I speak quickly

So όταν μιλάω γρήγορα is exactly what you would expect.

Greek is not saying only one specific future event here. It is describing a repeated situation.

Yes. Both are standard forms of the verb to speak.

• μιλάω
• μιλώ

Both mean I speak / I am speaking.

So you could also say:

• όταν μιλώ γρήγορα

That sounds a bit more concise or formal to some speakers, but both are correct and common.

Here γρήγορα is an adverb, meaning quickly / fast.

It describes the verb μιλάω:

• μιλάω γρήγορα = I speak quickly

Compare:

• γρήγορος = fast (masculine adjective)
• γρήγορη = fast (feminine adjective)
• γρήγορο = fast (neuter adjective)
• γρήγορα = quickly / fast (adverb)

So in this sentence, it is modifying the action, not the noun.

Greek word order is more flexible than English word order.

The sentence:

• Αυτή η συλλαβή είναι δύσκολη για μένα όταν μιλάω γρήγορα.

is perfectly natural. But Greek could also move some parts around for emphasis, for example:

• Όταν μιλάω γρήγορα, αυτή η συλλαβή είναι δύσκολη για μένα.

This puts more focus on the when I speak quickly part.

So the original order is normal, but not the only possible one.

Yes, but it usually is not necessary.

Greek verb endings already show the person:

• μιλάω = I speak

So Greek normally leaves out εγώ unless there is emphasis or contrast.

• όταν μιλάω γρήγορα = normal, neutral
• όταν εγώ μιλάω γρήγορα = more emphatic, like when I speak quickly (perhaps contrasting with someone else)

In most everyday sentences, omitting εγώ is the natural choice.

Yes. Αυτή η is pronounced as two words.

Very roughly:

• Αυτή = af-TI
• η = ee

So together it is something like:

• af-TI ee si-la-VEE...

In natural speech, the words flow together smoothly, but both are still there. Greek spelling keeps both because they have different grammatical jobs:

• αυτή = demonstrative
• η = article

A useful breakdown is:

• Αυτή = this
• η = the
• συλλαβή = syllable
• είναι = is
• δύσκολη = difficult
• για μένα = for me
• όταν = when
• μιλάω = I speak / I am speaking
• γρήγορα = quickly

So the structure is:

• This syllable is difficult for me when I speak quickly.

This kind of breakdown helps show how Greek builds the sentence grammatically, even if the English translation is already known.