Όταν έχω άγχος, μιλάω άσχημα ελληνικά.

Because Greek often leaves out subject pronouns when the verb ending already shows the person.

• έχω already means I have
• μιλάω already means I speak

So εγώ is not necessary. You would add εγώ only for emphasis or contrast.

Example: Εγώ μιλάω άσχημα ελληνικά, όχι αυτός.
Meaning: I speak Greek badly, not him.

Όταν means when or whenever.

In this sentence, the two present-tense verbs show a usual/repeated situation:

• Όταν έχω άγχος = when/whenever I am stressed
• μιλάω άσχημα ελληνικά = I speak Greek badly

So the whole sentence means something like Whenever I’m stressed, I speak Greek badly.

Greek often uses the present tense like this for habits or repeated reactions.

Usually, no—not if you want the same meaning.

• όταν = when / whenever
• αν = if

So:

• Όταν έχω άγχος means this is something that really happens, or happens regularly.
• Αν έχω άγχος means if I am stressed, which sounds more conditional or hypothetical.

In this sentence, όταν is the better choice because it describes a recurring situation.

Because άγχος is a noun, and Greek very naturally uses έχω with it.

So:

• έχω άγχος = literally I have stress/anxiety
• natural English meaning = I’m stressed / I feel anxious

You can also say:

• είμαι αγχωμένος if you are male
• είμαι αγχωμένη if you are female

That also means I am stressed.

So Greek has more than one natural way to express this idea.

Μιλάω is the normal verb for speak / talk.

• μιλάω and μιλώ mean the same thing
• μιλάω is very common in everyday speech
• μιλώ is also correct, and may sound slightly more formal or concise

So both of these are fine:

• Μιλάω ελληνικά
• Μιλώ ελληνικά

But λέω means say / tell, not speak a language.

So you say:

• μιλάω ελληνικά = I speak Greek

not:

• λέω ελληνικά

Because άσχημα is the form that fits this pattern.

A useful way to think about it is this:

• ελληνικά is a neuter plural form used for the language Greek
• words that go with it often appear in the same neuter plural form:
  • καλά ελληνικά
  • σωστά ελληνικά
  • άσχημα ελληνικά

Also, άσχημα is the same form used as an adverb meaning badly.

So for a learner, the easiest idea is:

• μιλάω άσχημα ελληνικά = I speak bad Greek / I speak Greek badly

You would not use άσχημος here, because that is the masculine singular form.

Ελληνικά is the standard way to say Greek as a language.

Historically and grammatically, it is a neuter plural form, but for learners the main thing is to memorize it as the normal language word after verbs like:

• μιλάω ελληνικά = I speak Greek
• μαθαίνω ελληνικά = I learn Greek

It is not plural in meaning. It just means Greek.

There is no article here because after verbs like μιλάω, Greek usually uses language names without an article.

Compare:

• Μιλάω ελληνικά. = I speak Greek.
• Τα ελληνικά είναι δύσκολα. = Greek is difficult.

In the second sentence, τα ελληνικά is acting more like a noun phrase: the Greek language / Greek.

No. Greek word order is fairly flexible.

The given sentence:

• Όταν έχω άγχος, μιλάω άσχημα ελληνικά.

is natural because it puts the time/situation first.

You could also say:

• Μιλάω άσχημα ελληνικά όταν έχω άγχος.

That is also correct.

The first version sounds a bit more like setting the scene first: when I’m stressed, this happens.

Also, when the όταν clause comes first, Greek normally separates it with a comma.

It is understandable, but many speakers would more naturally say:

• Όταν έχω άγχος, δεν μιλάω καλά ελληνικά.

That literally means When I’m stressed, I don’t speak Greek well, and it is a very common, natural way to express the idea.

Why? Because άσχημα can sometimes also suggest unpleasantly, rudely, or in an ugly way, depending on context. With ελληνικά, people will understand that you mean poorly, but δεν μιλάω καλά ελληνικά is often the safer everyday choice.

A rough English-friendly pronunciation is:

O-tan EH-kho ANG-hos, mee-LA-o A-shee-ma e-lee-nee-KA

A few helpful notes:

• Όταν = O-tan
• έχω = EH-kho
  The χ is not an English h. It is closer to the ch in Bach or loch.
• άγχος = ANG-hos
  The γχ combination sounds roughly like ngh.
• μιλάω = mee-LA-o
• άσχημα = A-shee-ma
• ελληνικά = e-lee-nee-KA

The accent mark shows which syllable gets the stress.