Policija čuva zatvor.

In Croatian, policija is a singular feminine noun. It refers to the police as an institution or force, not to individual police officers.

So:

• policija čuva = the police guards / is guarding
• not policija čuvaju

If you want to talk about individual police officers, you would use a different noun, such as:

• policajac = police officer, policeman
• policajci = police officers, policemen

So even though English says the police are, Croatian says policija je or policija čuva, with singular agreement.

In this sentence:

• policija is in the nominative singular because it is the subject
• zatvor is in the accusative singular because it is the direct object

So the structure is:

• Policija = who is doing the action
• čuva = the action
• zatvor = what is being guarded

A useful thing to notice is that zatvor is a masculine inanimate noun, and in Croatian, masculine inanimate nouns often have the same form in nominative and accusative singular. That is why it stays zatvor, not zatvora.

Because zatvor is a masculine inanimate noun, and for that group of nouns, the accusative singular is usually the same as the nominative singular.

So:

• nominative: zatvor
• accusative: zatvor

By contrast, masculine animate nouns usually change in the accusative:

• policajac → policajca

That is an important pattern in Croatian:

• masculine animate: accusative often matches genitive
• masculine inanimate: accusative often matches nominative

Since a prison is inanimate, zatvor does not change here.

Croatian does not have articles like English a or the.

So:

• Policija čuva zatvor can mean The police guard the prison
• depending on context, it could also be understood more generally as Police guard a prison or The police are guarding the prison

Croatian usually leaves definiteness to:

• context
• word order
• stress
• the broader situation

So it is completely normal that there is no separate word for the.

Čuva is the 3rd person singular present tense of čuvati.

Its core meanings include:

• to guard
• to protect
• to watch over
• sometimes to keep

In this sentence, čuva most naturally means:

• guards
• is guarding
• watches over

Because Croatian present tense can correspond to both the English simple present and present continuous, this sentence could mean:

• The police guard the prison
• The police are guarding the prison

The exact English translation depends on context.

The infinitive is čuvati.

This is an imperfective verb, which means it typically describes:

• ongoing action
• repeated action
• habitual action
• general activity

So Policija čuva zatvor can suggest:

• a general fact
• an ongoing action
• a repeated duty

The perfective partner is often sačuvati, but that verb more often means to preserve, to save, or to keep safe, not simply to guard in every context. So for the idea of guarding a prison, čuvati is the natural verb.

Yes. Croatian word order is more flexible than English because case endings help show grammatical roles.

The most neutral order here is:

• Policija čuva zatvor.

But other orders are possible, for example:

• Zatvor čuva policija.

This still means The police guard the prison, but it shifts the emphasis. It might sound like:

• It is the police who guard the prison
• or it puts more focus on zatvor

So the basic meaning can stay the same, but the focus or style changes.

A simple approximate pronunciation for an English speaker is:

• Policija ≈ po-lee-TSEE-ya
• čuva ≈ CHOO-va
• zatvor ≈ ZAHT-vor

A few useful sound notes:

• č sounds like ch in church, but often a bit firmer
• c in Croatian sounds like ts
• j sounds like English y
• v is like English v
• Croatian pronunciation is generally quite regular, so words are usually pronounced close to how they are spelled

Yes, policija is a feminine singular noun.

That matters because verbs and adjectives can agree with it in certain contexts. In the present tense here, you see singular agreement in:

• čuva = she/it guards form, grammatically speaking

If you added an adjective, it would also be feminine singular:

• Hrvatska policija čuva zatvor. = The Croatian police guard the prison.

So yes, its gender is grammatically important, even though the meaning is not specifically female.

Usually no, not in natural English.

Although čuvati can sometimes mean to keep, in this sentence the most natural meaning is to guard / protect / watch over.

So:

• Policija čuva zatvor. = The police guard the prison / are guarding the prison

If you translated it as keep the prison, that would sound unnatural in English unless a very special context made it clear.

You usually know from context.

Croatian present tense often covers both:

• simple present: The police guard the prison
• present continuous: The police are guarding the prison

So Policija čuva zatvor could mean either:

• this is their regular function
• this is happening now

To make the time reference clearer, Croatian may add adverbs or context, for example:

• Policija sada čuva zatvor. = The police are guarding the prison now
• Policija uvijek čuva zatvor. = The police always guard the prison

Without extra context, both readings are possible.