Chiudi la finestra della cucina prima che entri la pioggia, per favore.

Chiudi is the informal singular imperative of chiudere (to close).

So it is the form you use when telling one person you know well to do something:

• Chiudi la porta. = Close the door.
• Chiudi la finestra. = Close the window.

It looks exactly like the tu form of the present tense (tu chiudi), so context tells you whether it means you close or close!
Here, it is clearly a command.

It is informal singular, because of chiudi.

If you wanted other levels of politeness, you would change the verb:

• Chiudi la finestra... = informal, to one person
• Chiuda la finestra... = formal, to one person
• Chiudete la finestra... = to more than one person

Per favore makes the sentence polite, but the verb form still tells you whether it is informal or formal.

Italian uses definite articles much more often than English.

• la finestra = the window
• della cucina = of the kitchen

In English, we often say the kitchen window, using one noun as an adjective.
Italian usually expresses that idea as:

• la finestra della cucina
• literally: the window of the kitchen

So della is just di + la:

• di + la = della

Because Italian normally links the two nouns with di.

English often does this:

• kitchen window
• bedroom door
• car engine

Italian usually prefers:

• la finestra della cucina
• la porta della camera
• il motore della macchina

So for an English speaker, this is a very common pattern to get used to: Italian often says the X of the Y where English says the Y X.

Because prima che is followed by a conjugated verb, while prima di is followed by an infinitive.

Here we have:

• prima che entri la pioggia

Since entri is a full verb form, che is needed.

Compare:

• Chiudi la finestra prima che entri la pioggia.
  = before the rain comes in

• Chiudi la finestra prima di uscire.
  = before going out / before you go out

A useful rule:

• prima di + infinitive
• prima che + subjunctive

Because prima che normally requires the subjunctive in Italian.

The verb entrare in the present subjunctive, third person singular, is:

• che entri

So:

• prima che entri la pioggia = before the rain comes in

If you used entra, that would be the indicative, and it would not fit the usual grammar after prima che.

This is one of the most important patterns to learn:

• prima che + subjunctive

Other examples:

• Aspetta qui finché non arrivi Marco.
• Ti chiamo prima che sia troppo tardi.

The subject is la pioggia.

So the clause means:

• che entri la pioggia
• literally: that the rain come in

Even though la pioggia comes after the verb, it is still the subject.

This word order is normal in Italian. English usually prefers the rain comes in, but Italian often allows or prefers entri la pioggia, especially when the action comes first.

Yes. Prima che la pioggia entri is also grammatically correct.

Both are possible:

• prima che entri la pioggia
• prima che la pioggia entri

The version with the subject after the verb can sound a little more natural or flowing in this kind of sentence, but both are understandable and correct.

Italian has more flexible word order than English, so learners should not expect the subject to always come before the verb.

Yes. In Italian, entrare is very natural here.

It means that the rain comes in, for example through an open window.

English also says things like:

• before the rain gets in
• before the rain comes in

So the idea is the same. Italian is simply using entrare in a normal, literal way.

If you wanted to be more explicit, you could say:

• prima che entri la pioggia in casa
• prima che la pioggia entri dalla finestra

But in your sentence, the place is already obvious from context.

Yes, per favore is flexible.

It can appear:

• at the end: Chiudi la finestra..., per favore.
• at the beginning: Per favore, chiudi la finestra...
• sometimes in the middle

Putting it at the end is very common and natural.

So these are all possible:

• Chiudi la finestra della cucina, per favore.
• Per favore, chiudi la finestra della cucina.

The meaning stays the same; the difference is mostly rhythm and emphasis.

Yes. If the window is already understood, you can use a direct object pronoun.

With an affirmative imperative, the pronoun attaches to the end of the verb:

• Chiudila = close it

So you could say:

• Chiudila prima che entri la pioggia, per favore.

That comes from:

• chiudi + la = chiudila

This is a very useful pattern with commands:

• Prendilo = take it
• Aprila = open it
• Scrivimi = write to me

Yes. Pioggia is a feminine noun, so it takes:

• la pioggia

That is also why, if you referred back to it with an adjective or pronoun, you would use feminine agreement.

For example:

• La pioggia è forte.
• È arrivata presto.

So in your sentence, la is simply the normal feminine singular article.

The dictionary forms are:

• chiudere = to close
• entrare = to enter / to come in

And the forms used here are:

• chiudi = informal singular command from chiudere
• entri = present subjunctive, third person singular, from entrare

Seeing both the dictionary form and the actual sentence form is useful, because Italian changes verbs quite a lot depending on mood and person.

Yes, it is natural and understandable.

It sounds like something you might say in a real situation, especially if rain is starting and a kitchen window is open.

A few natural variants would also be:

• Chiudi la finestra della cucina prima che entri la pioggia.
• Chiudi la finestra in cucina prima che entri la pioggia.
• Per favore, chiudi la finestra della cucina prima che entri la pioggia.

So the sentence is good Italian, and it also shows a very useful grammar point: prima che + subjunctive.