Το γάλα χαλάει γρήγορα το καλοκαίρι.

In Greek, it is very common to use the definite article with general nouns, even when English would use no article.

So το γάλα here means milk in a general sense, not necessarily the milk in a specific carton or bottle.

This is one of the big differences from English:

• English: Milk spoils quickly in summer
• Greek: Το γάλα χαλάει γρήγορα το καλοκαίρι

So the article is normal Greek usage, not something you should always translate as the.

It is singular.

Γάλα is a neuter singular noun meaning milk. Even though milk is a mass noun, Greek treats it grammatically as singular here, so the verb is also singular: χαλάει.

That is why you do not see a plural verb.

Χαλάει is the 3rd person singular present tense form of χαλάω.

Here it means:

• spoils
• goes bad

The same verb can also mean:

• breaks
• ruins
• damages

So the verb has a broad meaning, and the context tells you which English word fits best. With food like γάλα, the natural meaning is spoils or goes bad.

Greek often leaves out subject pronouns because the verb ending already shows the person and number.

So instead of saying something like it spoils, Greek can simply say χαλάει.

The ending -ει tells you it is 3rd person singular, so a separate pronoun is usually unnecessary.

Γρήγορα is an adverb, and it means quickly.

It describes how the milk spoils.

Compare:

• γρήγορος / γρήγορη / γρήγορο = quick, fast (adjective)
• γρήγορα = quickly, fast (adverb)

So in this sentence, γρήγορα modifies the verb χαλάει, not the noun γάλα.

Yes. Greek word order is more flexible than English word order.

This sentence is natural as it stands:

• Το γάλα χαλάει γρήγορα το καλοκαίρι.

But you could also hear:

• Το γάλα το καλοκαίρι χαλάει γρήγορα.
• Το καλοκαίρι το γάλα χαλάει γρήγορα.

The basic meaning stays the same, but the emphasis shifts a little. The original version sounds neutral and natural.

Because καλοκαίρι is also a noun, and Greek normally uses the article with seasons in expressions like this.

So:

• το καλοκαίρι = in summer / in the summer
• τον χειμώνα = in winter
• την άνοιξη = in spring

Again, the Greek article does not always match English article usage exactly.

Greek often expresses time with the article + noun in the accusative, without needing a preposition.

So:

• το καλοκαίρι = in the summer / during the summer
• το πρωί = in the morning
• την Κυριακή = on Sunday

This is very normal Greek. English needs in here, but Greek often does not.

It is in the accusative singular.

In Greek, many expressions of time use the accusative. Here το καλοκαίρι functions as a time expression meaning during summer.

Because καλοκαίρι is a neuter noun, its nominative and accusative forms look the same:

• nominative: το καλοκαίρι
• accusative: το καλοκαίρι

So the form does not change, but its function in the sentence is adverbial: it tells you when something happens.

In this sentence, it most naturally means summer in general or during the summer as a general fact.

So the sentence sounds like a general truth:

• Milk spoils quickly in summer.

With enough context, το καλοκαίρι can sometimes refer to a specific summer, including this summer, but that is not the most likely reading here.

Yes.

Χαλάει is in the present tense, and Greek uses the present tense very naturally for:

• general truths
• habits
• repeated situations

So this sentence is not only about one specific occasion. It expresses something generally true:

• milk spoils quickly in summer

This works very much like the English present simple.

A rough pronunciation guide is:

to GHA-la kha-LA-ee GHREE-go-ra to ka-lo-KE-ri

A few useful notes:

• γ in γάλα is not a hard English g; it is a softer sound
• χ in χαλάει is like the ch in Scottish loch or German Bach
• αι in καλοκαίρι sounds like e
• the stress falls on:
  • γάλα
  • χαλάει
  • γρήγορα
  • καλοκαίρι

So the rhythm is: Το ΓΑ-λα χα-ΛΑ-ει ΓΡΗ-go-ra το ka-lo-KE-ri