Η μεγαλύτερη δυσκολία για μένα είναι να μιλάω χωρίς να σκέφτομαι κάθε λέξη.

Because δυσκολία (difficulty) is a feminine singular noun, so the article and adjective must match it:

• η = feminine singular the
• μεγαλύτερη = feminine singular form of bigger / greater / biggest / greatest
• δυσκολία = difficulty

So η μεγαλύτερη δυσκολία means literally the greatest difficulty or the biggest difficulty.

Greek adjectives agree with the noun in gender, number, and case, so that is why all three words line up this way.

Formally, μεγαλύτερη is the comparative form of μεγάλη (big).
But in Greek, the comparative is very often used with the definite article to express a superlative meaning.

So:

• μεγάλη δυσκολία = a big difficulty
• μεγαλύτερη δυσκολία = a bigger difficulty
• η μεγαλύτερη δυσκολία = the biggest / greatest difficulty

This is very common in modern Greek.

για μένα means for me.

• για = for
• μένα = me

So the phrase marks a personal point of view:

• Η μεγαλύτερη δυσκολία για μένα...
  = The greatest difficulty for me...

This is a very natural Greek way to say it.

Because εγώ is the subject form (I), while μένα is the oblique form used after prepositions like για.

Compare:

• εγώ μιλάω = I speak
• για μένα = for me

So after για, you need μένα, not εγώ.

Greek often uses a να-clause where English might use an infinitive.

English says:

• The hardest thing is to speak...

Modern Greek does not normally use an infinitive the way English does. Instead, it says:

• Η μεγαλύτερη δυσκολία είναι να μιλάω...
• literally: The greatest difficulty is that I speak / to be speaking...
• naturally: The greatest difficulty is speaking... or is to speak...

So να + verb is the normal structure here.

να is a very common particle in Greek. It usually introduces a verb in a subordinate clause, often corresponding to things like:

• to
• that
• forms used after modal expressions, wishes, purpose, etc.

In this sentence, it appears twice:

• είναι να μιλάω
• χωρίς να σκέφτομαι

In both places, να introduces the verb clause.

A useful thing to remember is that in modern Greek, να + verb often does work that English infinitives do.

Because the sentence is talking about a general ongoing ability/problem, not a single completed act.

• μιλάω = present/imperfective stem
  → speaking in general, habitually, continuously
• μιλήσω = aorist/perfective stem
  → speak once, as a complete act

Here the meaning is:

• to speak without thinking about every word
• meaning to speak fluently / continuously, not just to say something once

So να μιλάω is the natural choice.

For the same reason: the sentence describes an ongoing mental process.

• να σκέφτομαι κάθε λέξη = to be thinking about every word
• να σκεφτώ would sound more like to think of / think through once, as a complete act

Since the idea is without constantly thinking about every single word while speaking, Greek uses the imperfective form:

• χωρίς να σκέφτομαι

χωρίς means without.
When it is followed by a verb, Greek normally uses χωρίς να + verb.

So:

• χωρίς να σκέφτομαι = without thinking

This is a very common pattern:

• χωρίς να μιλάει = without speaking
• χωρίς να ξέρει = without knowing
• χωρίς να περιμένουμε = without waiting

So if English uses without + -ing, Greek often uses χωρίς να + verb.

Because Greek verb endings usually already show the subject.

Here:

• μιλάω = I speak / I am speaking
• σκέφτομαι = I think / I am thinking

So Greek does not need to say εγώ unless it wants extra emphasis or contrast.

For example:

• να μιλάω = for me to speak / to speak
• να μιλάω εγώ = for me to speak (emphatic)

In your sentence, no emphasis is needed, so the pronoun is omitted.

Because κάθε (each / every) is followed by the noun in the form that fits its role in the sentence.

Here λέξη is the object of σκέφτομαι, so it appears in the ordinary singular form used here:

• κάθε λέξη = every word

Also, κάθε normally does not take the definite article:

• κάθε μέρα = every day
• κάθε φορά = every time
• κάθε λέξη = every word

So κάθε λέξη is exactly what you expect.

Yes, completely normal.

Just like English says every word in the singular, Greek also uses the singular after κάθε:

• κάθε λέξη = every word
• κάθε μέρα = every day
• κάθε άνθρωπος = every person

So this matches English quite closely.

δυσκολία is in the nominative singular because it is the subject of the sentence.

The structure is:

• Η μεγαλύτερη δυσκολία ... είναι ...
• The greatest difficulty ... is ...

Since it is the thing being described by είναι, it stays in the nominative.

είναι is the present tense of είμαι (to be), third person singular:

• είμαι = I am
• είσαι = you are
• είναι = he/she/it is

Here it agrees with the subject η μεγαλύτερη δυσκολία, which is singular:

• Η μεγαλύτερη δυσκολία ... είναι ...
• The greatest difficulty ... is ...

Yes. Both are correct.

• μιλάω
• μιλώ

Both mean I speak / I am speaking.
In many contexts they are interchangeable, though μιλάω is often felt as slightly more everyday or conversational.

So you could also say:

• Η μεγαλύτερη δυσκολία για μένα είναι να μιλώ χωρίς να σκέφτομαι κάθε λέξη.

That is still correct.

Yes, Greek word order is fairly flexible.

The given sentence is very natural:

• Η μεγαλύτερη δυσκολία για μένα είναι...

But you could also hear:

• Για μένα, η μεγαλύτερη δυσκολία είναι...

That version puts a little more emphasis on for me.

So:

• Η μεγαλύτερη δυσκολία για μένα... = neutral, smooth
• Για μένα, η μεγαλύτερη δυσκολία... = slightly more emphasis on your personal perspective

Both are good.

They would understand it as:

• without having to think about each individual word
• without mentally translating or choosing every word one by one

So the idea is not just literal thinking, but the broader speaking problem of not yet being fully automatic or fluent.

In other words, the sentence suggests:

• speaking spontaneously
• speaking naturally
• speaking without stopping to plan every word

A few, yes:

• μεγαλύτερη
  Stress falls on λύ: me-ga-LY-te-ri

• δυσκολία
  Stress falls on the last syllable: dhi-sko-li-A

• μιλάω
  Stress on λά: mi-LA-o

• σκέφτομαι
  Stress on σκέφ: SKEF-to-me

• λέξη
  Stress on λέ: LEK-si

Also, some consonants may feel unfamiliar to English speakers:

• δ in δυσκολία is like th in this
• θ (not in this sentence, but common in Greek) is like th in think
• χ in χωρίς is not like English h exactly; it is a rougher sound

A very useful pattern is:

• Το/Η ... είναι να + verb
• χωρίς να + verb

So from this one sentence, you can learn two important structures:

1. είναι να + verb
   Used where English might use is to... or is ...-ing

   • Η δυσκολία είναι να καταλαβαίνω γρήγορα.
   • The difficulty is understanding quickly.

2. χωρίς να + verb
   Used for without doing

   • Μιλάει χωρίς να σταματά.
   • He speaks without stopping.

These are very common and worth remembering as chunks.