Poliția îl poate aresta mâine.

Because Romanian usually puts the definite article at the end of the noun.

• poliție = police
• poliția = the police

So the final -a is the definite article here.

In this sentence, poliția is grammatically singular. Romanian often treats the police as a single institution, so the verb is singular too:

• Poliția poate... = The police can...

If you want to talk about the police officers as individual people, Romanian often uses polițiștii = the police officers, which is plural.

Yes, poliție is a feminine noun in Romanian.

That matters for things like:

• articles
• adjectives
• pronouns that refer back to it

In this sentence, the verb poate does not show gender, so you do not see feminine agreement directly there. But the noun itself is feminine.

îl is the unstressed direct object pronoun meaning him here.

So:

• Poliția îl poate aresta mâine = The police can arrest him tomorrow

It is masculine singular. In other contexts, îl can also refer to a masculine singular noun meaning it, but here it means him.

Because Romanian object pronouns like îl usually go before the conjugated verb.

Here, the conjugated verb is poate, not aresta:

• îl poate aresta = literally something like him can arrest

That sounds strange in English, but it is normal in Romanian.

Because poate is the conjugated verb, and aresta stays in the infinitive.

• poate = can
• aresta = arrest

So poate aresta means can arrest.

This is like English, where only can changes:

• he can arrest not
• he can arrests

poate is the 3rd person singular present tense of a putea, which means to be able to / can.

So:

• eu pot = I can
• el/ea poate = he/she/it can

Since poliția is singular, Romanian uses poate.

It can cover all of those ideas depending on context.

In this sentence, poate most naturally means something like:

• can
• is able to
• possibly may in the sense of permission or possibility

So the sentence does not necessarily mean the arrest will definitely happen. It says that the police have the ability, possibility, or authority to arrest him tomorrow.

Yes. That is a very common alternative.

You will often see both patterns in Romanian:

• Poliția îl poate aresta mâine
• Poliția poate să-l aresteze mâine

Both are correct. Very roughly:

• the infinitive version îl poate aresta can sound a bit more compact or formal
• the să
  • subjunctive version is very common in everyday Romanian

Yes, Romanian word order is fairly flexible.

For example, you can also say:

• Mâine, poliția îl poate aresta.

That still means the same thing, but it puts more focus on tomorrow.

What is less flexible is the position of the clitic pronoun îl. It normally stays before the conjugated verb:

• îl poate aresta is normal
• poate îl aresta is not the standard pattern here

Because îl already is the direct object pronoun by itself.

You often see pe with full human direct objects or stressed pronouns, for example:

• Poliția îl poate aresta pe suspect mâine.
• Poliția îl poate aresta pe el mâine.

But when the object is just the clitic pronoun îl, no pe is needed.

A simple approximate pronunciation is:

po-li-ȚI-a îl POA-te a-res-TA MÂI-ne

A few useful sound notes:

• ț sounds like ts in cats
• ă is a short neutral vowel, similar to uh
• î and â are the same sound in modern Romanian, and they do not have an exact English equivalent
• mâine is stressed on the first syllable

So poliția sounds roughly like po-lee-TSEE-a.