Policija puca.

Because policija is a singular noun in Croatian. Grammatically, it is feminine singular, so it takes the singular verb form puca.

So Croatian says:

• Policija puca. = The police are shooting.

Even though English treats police as plural, Croatian treats policija as singular.

If you want to talk about individual police officers, you would use a plural noun, for example:

• Policajci pucaju. = The police officers are shooting.

Puca is the 3rd person singular present tense of the verb pucati.

So:

• ja pucam = I shoot / am shooting
• ti pucaš = you shoot / are shooting
• on/ona/ono puca = he/she/it shoots / is shooting

Here it agrees with policija, which is singular.

It can mean either one, depending on context.

Croatian present tense often covers both:

• simple present: The police shoot
• present continuous: The police are shooting

So puca does not by itself tell you whether the action is habitual or happening right now. The surrounding context does that.

Because Croatian does not have articles like a or the.

So policija can mean:

• police
• the police

You understand the exact sense from context.

It is in the nominative case, because it is the subject of the sentence.

In Policija puca, the structure is basically:

• Policija = subject
• puca = verb

So this is the basic subject + verb pattern.

Yes. Pucati is imperfective.

That matters because imperfective verbs are commonly used for:

• ongoing actions
• repeated actions
• general actions

So Policija puca naturally fits meanings like:

• The police are shooting
• The police shoot
• The police keep shooting

If you wanted a perfective idea such as shot once or started shooting, Croatian would usually use a different verb form or a different verb.

Yes. Policija puca is the most neutral word order, but Croatian word order is fairly flexible.

For example:

• Policija puca. = neutral
• Puca policija. = possible, but more marked; it can sound like the speaker is emphasizing the action or the subject in a particular context

So the standard learner-friendly version is Policija puca.

A rough English-friendly pronunciation is:

po-LEE-tsee-ya POO-tsa

A few useful sound notes:

• c in Croatian is pronounced like ts in cats
• č and ć are different letters, but there is no č/ć here
• every written vowel is pronounced clearly

So:

• Policija → po-LEE-tsee-ya
• puca → POO-tsa

Yes. The verb pucati can have several meanings depending on context, including ideas like:

• to shoot / fire
• to burst
• to crack

But in Policija puca, the most natural interpretation is the one you were given in the translation. The subject policija strongly guides the meaning.

Because Croatian normally does not build the present continuous with a separate auxiliary the way English does.

English uses:

• is shooting

Croatian usually just uses the present tense form:

• puca

So one Croatian present-tense verb can correspond to both:

• shoots
• is shooting

That is very normal in Croatian.