Learn Hardcore Greek: Εγώ μιλάω αγγλικά και εσύ μιλάς πολύ καλά.

Natural without pronouns: Μιλάω αγγλικά και μιλάς πολύ καλά.
With emphasis/contrast (as in the original): Εγώ μιλάω… και εσύ μιλάς…
Note: εσύ is the subject form (“you” as doer). Don’t use σε here; σε is the object form (“you” as receiver).

Which is correct, μιλάω or μιλώ? What about the other forms?

Both are correct; μιλάω is the more common everyday form, while μιλώ is a shorter/neutral variant. Present tense forms (both variants shown where common):

εγώ: μιλάω / μιλώ
εσύ: μιλάς
αυτός/αυτή/αυτό: μιλάει / μιλά
εμείς: μιλάμε / μιλούμε
εσείς: μιλάτε
αυτοί/αυτές/αυτά: μιλάνε / μιλούν(ε) All of these are standard; some are more formal or regionally preferred.

Why is αγγλικά plural and why is there no article (τα)?

Languages like English, Greek, French, etc., are typically neuter plural in Greek: αγγλικά, ελληνικά, γαλλικά.
After verbs like μιλάω (speak), the article is normally omitted: μιλάω αγγλικά = “I speak English.”
You use the article when you treat the language as a noun/topic: Τα αγγλικά μου είναι καλά (“My English is good”).

Can I say μιλάω τα αγγλικά?

No, that sounds unidiomatic. Say μιλάω αγγλικά. Use τα αγγλικά only when the language is the subject or a general topic (e.g., Τα αγγλικά είναι δύσκολα).

Why is it καλά and not καλός?

Because you need an adverb (“well”), not an adjective (“good”).

καλός = good (adjective; describes a noun)
καλά = well (adverb; describes the verb “speak”)
So: μιλάς πολύ καλά = “you speak very well.”

Does πολύ change form here?

Here πολύ is an adverb (“very”) and is invariable: πολύ καλά = “very well.”
When πολύ is an adjective (“many/much”), it does change: πολλοί άνθρωποι (many people), πολλή δουλειά (a lot of work), πολύ νερό (much water).
You can intensify with πάρα πολύ: μιλάς πάρα πολύ καλά (“you speak extremely well”).

Is the word order fixed? Where do πολύ καλά and αγγλικά go?

Greek word order is flexible. Common options:

Μιλάς πολύ καλά αγγλικά (very natural)
Μιλάς αγγλικά πολύ καλά (also fine)
With emphasis: Πολύ καλά μιλάς αγγλικά (fronting the adverbial for emphasis)
Avoid μιλάς καλά πολύ; it sounds unnatural.

Is it okay not to repeat αγγλικά in the second clause?

Yes. Ellipsis is natural when the meaning is clear across coordinated clauses.
Your sentence implies “…and you speak [English] very well.”
If you want to be explicit: Εγώ μιλάω αγγλικά και εσύ μιλάς αγγλικά πολύ καλά.

What about formal “you”? Should it be μιλάς or μιλάτε?

Informal singular: εσύ μιλάς
Formal singular or plural: εσείς μιλάτε
So formally you’d say: Εγώ μιλάω αγγλικά και εσείς μιλάτε πολύ καλά.

Can και become κι before εσύ?

Yes. και often becomes κι before a vowel for smoother pronunciation.
Both are correct: και εσύ / κι εσύ.

How do you pronounce αγγλικά? What sound does γγ make?

αγγλικά is pronounced [aŋgliˈka]. The double gamma γγ is pronounced like “ng” + “g” ([ŋg]), similar to “angle” but with a hard g: aŋg-li-KA.

Where is the stress in the sentence? Do ο and ω sound different in μιλάω?

Stress marks show which syllable to stress:

Εγώ [eˈɣo], μιλάω [miˈlao], αγγλικά [aŋgliˈka]
εσύ [eˈsi], μιλάς [miˈlas], πολύ [poˈli], καλά [kaˈla]
In Modern Greek, ο and ω are both pronounced /o/. In μιλάω, -άω is pronounced [áo] in two beats (often flowing together in speech).

Are language names capitalized in Greek?

No. Language names are written in lowercase: αγγλικά, ελληνικά, ισπανικά.
Country names are capitalized (e.g., Αγγλία), but adjectives of nationality and language names are not, unless they start a sentence.

What’s the difference between μιλάω, λέω, and ομιλώ?

μιλάω = speak (a language), talk: μιλάω αγγλικά (I speak English).
λέω = say/tell: Πώς το λέτε στα αγγλικά; (How do you say it in English?)
ομιλώ = speak (formal/literary). You’ll see it in announcements or formal speech.