Uvijek zatvaram prozor prije spavanja.

Croatian does not have articles like the or a/an.

So prozor can mean a window or the window, depending on context. In this sentence, the meaning is understood from the situation: I always close the window before sleeping.

If you need to be more specific in Croatian, you usually do it with context, word order, or extra words such as taj (that) or ovaj (this), not with an article.

Zatvaram is the 1st person singular present tense of zatvarati / zatvaram.

It literally means I close or I am closing, but here it is used for a habitual action, so the natural English meaning is:

I always close the window before sleeping.

Croatian often uses the present tense for routines and repeated actions, just like English does in sentences such as I always lock the door.

Because this sentence describes a habit or repeated action, Croatian normally uses the imperfective verb: zatvaram.

• zatvarati / zatvaram = imperfective, focusing on the action as repeated or ongoing
• zatvoriti / zatvorim = perfective, focusing on one completed action

So:

• Uvijek zatvaram prozor... = I always close the window...
• Zatvorim prozor... would sound more like I close the window (once / completely), and in many contexts the perfective present is not the natural choice for general habits.

For routines, zatvaram is the normal form.

Because prozor is the direct object of zatvaram (I close what? — the window), so it is in the accusative case.

However, prozor is a masculine inanimate noun, and for many masculine inanimate nouns, the accusative singular looks exactly the same as the nominative singular.

So:

• nominative: prozor
• accusative: prozor

That is why the form does not visibly change here.

The preposition prije requires the genitive case.

That is why you get:

• prije spavanje ❌
• prije spavanja ✅

So spavanja is the genitive singular form.

This is a very useful pattern to remember:

• prije ručka = before lunch
• prije škole = before school
• prije spavanja = before sleeping / before bed

In this sentence, spavanja is functioning as a noun, not as a finite verb.

It comes from spavanje, which is a verbal noun meaning sleeping.

So:

• spavati = to sleep
• spavanje = sleeping
• prije spavanja = before sleeping

English also does something similar with forms like before leaving, after eating, and during training.

Not naturally in this context.

Prije spavanja is the normal, compact way to say before sleeping / before going to sleep.

If you want a full clause, Croatian would usually say something more like:

• prije nego što odem spavati = before I go to sleep
• prije nego što zaspim = before I fall asleep

But for a general habit, prije spavanja is the simplest and most natural option.

Yes. Croatian word order is fairly flexible, although not completely free.

The basic sentence is:

Uvijek zatvaram prozor prije spavanja.

But you could also say:

• Prije spavanja uvijek zatvaram prozor.
• Prozor uvijek zatvaram prije spavanja.

These versions all mean roughly the same thing, but the emphasis changes slightly:

• Uvijek at the beginning highlights always
• Prije spavanja at the beginning highlights the time
• Prozor at the beginning can give contrastive emphasis, like the window is what I close

The original version is neutral and very natural.

Uvijek usually means always, and it can appear in different places depending on emphasis.

Common positions include:

• Uvijek zatvaram prozor prije spavanja.
• Zatvaram prozor uvijek prije spavanja.
• Prije spavanja uvijek zatvaram prozor.

The first and third are more natural for most learners.

Putting uvijek near the beginning is very common because it clearly marks the sentence as a habit or routine.

Literally, it means before sleeping.

In real usage, though, it often corresponds to what English speakers mean by before bed or before going to sleep, depending on context.

So in this sentence, the practical meaning is something like:

I always close the window before I go to sleep.

It does not usually mean before sleep in general in some abstract sense; it refers to the normal bedtime routine.

Yes, it is completely natural.

It sounds like a normal statement about a personal routine:

Uvijek zatvaram prozor prije spavanja.

Why it sounds natural:

• uvijek clearly marks a habit
• zatvaram is the correct imperfective verb for a repeated action
• prozor is the normal direct object form
• prije spavanja is a very common time expression

So this is a good model sentence for everyday Croatian.