Η φίλη μου κοιμάται καλύτερα όταν ο ανεμιστήρας είναι ανοιχτός και το παντζούρι είναι λίγο κλειστό.

In Greek, a noun with a possessive like μου usually still takes the definite article when you mean a specific person or thing. So η φίλη μου literally looks like the friend my, but it simply means my friend.

English normally says my friend without the. Greek usually keeps the article.

The short possessive forms such as μου, σου, του, της, μας, σας, τους normally come after the noun.

So:

• η φίλη μου = my friend
• ο αδερφός της = her brother
• το σπίτι μας = our house

This is the normal Greek pattern. English speakers often expect the possessive to come first, but Greek usually places this short form after the noun.

Κοιμάται is the 3rd person singular form of κοιμάμαι, meaning to sleep.

It matches the subject η φίλη μου, which is singular: my friend sleeps.

A useful thing to know is that κοιμάμαι has middle/passive-style endings, even though its meaning is active. So κοιμάται does not mean is being slept. It simply means sleeps / is sleeping.

Some Greek verbs use middle/passive endings but have an active meaning. Κοιμάμαι is one of them.

So:

• κοιμάμαι = I sleep
• κοιμάσαι = you sleep
• κοιμάται = he/she/it sleeps

This is just how the verb is built in Modern Greek. It is very common, and learners gradually get used to these verbs.

Because καλύτερα is the comparative adverb of καλά.

Here it describes how she sleeps, not what kind of friend she is. So Greek needs an adverb:

• καλά = well
• καλύτερα = better

So κοιμάται καλύτερα means sleeps better.

Yes. Πιο καλά is also possible in everyday Greek, and it also means better.

But καλύτερα is very common and often sounds a bit more natural or compact in sentences like this.

So both can work:

• κοιμάται καλύτερα
• κοιμάται πιο καλά

Όταν means when and introduces a time clause.

So the structure is:

• main clause: Η φίλη μου κοιμάται καλύτερα
• time clause: όταν ο ανεμιστήρας είναι ανοιχτός και το παντζούρι είναι λίγο κλειστό

It tells us under what circumstances / at what time she sleeps better.

Because the sentence describes a general, repeated situation: she sleeps better whenever those conditions are true.

Greek often uses the present tense for this kind of habitual meaning, just as English can say:

• She sleeps better when the fan is on and the shutter is a little closed.

So the present here does not only mean right now. It can also describe something generally true.

Greek uses the definite article much more often than English.

In this sentence, ο ανεμιστήρας and το παντζούρι refer to the fan and the shutter in the situation being described, so Greek naturally uses the articles.

This often sounds more definite in Greek than it would in English, but it is normal Greek usage.

Here ανοιχτός means something like on / running for the fan.

Greek often uses ανοιχτός and κλειστός not only for things that are physically open or closed, but also for devices or systems that are on or off.

So with a fan:

• ο ανεμιστήρας είναι ανοιχτός = the fan is on

With things like windows, doors, shutters, etc., ανοιχτός / κλειστός usually keeps the more literal sense of open / closed.

Because adjectives in Greek must agree with the noun in gender, number, and case.

• ο ανεμιστήρας is masculine singular, so: ανοιχτός
• το παντζούρι is neuter singular, so: κλειστό

This is normal adjective agreement.

You can think of the basic singular forms as:

• masculine: ανοιχτός, κλειστός
• feminine: ανοιχτή, κλειστή
• neuter: ανοιχτό, κλειστό

Λίγο here means a little or slightly.

It modifies the idea of being closed, so λίγο κλειστό means a little closed or more naturally slightly closed / partly closed.

It softens the adjective and shows that the shutter is not fully closed.

Because the sentence describes a state, not an action.

• είναι ανοιχτός = is open / is on
• είναι κλειστό = is closed

If Greek used verbs like ανοίγει or κλείνει, that would suggest the action of opening or closing is happening.

Here the meaning is that the fan and shutter are already in those states.

Not completely. Greek word order is more flexible than English, because the endings help show what each word is doing.

The given order is natural and clear:

Η φίλη μου κοιμάται καλύτερα όταν ο ανεμιστήρας είναι ανοιχτός και το παντζούρι είναι λίγο κλειστό.

But Greek can move things around for emphasis. For example, καλύτερα or the whole όταν clause could be shifted in some contexts.

Still, for a learner, the original order is a very good neutral pattern to follow.

Because Greek usually does not need an explicit subject pronoun when the verb ending already shows the person and number.

Here κοιμάται already tells us it is he/she/it singular, and the subject η φίλη μου is already stated, so adding αυτή would usually be unnecessary.

Greek often leaves subject pronouns out unless they are needed for emphasis or contrast.