Preuzimanje prtljage počinje sada.

Preuzimanje is a verbal noun ending in -nje. It comes from the verb family preuzeti / preuzimati, meaning to take over, to collect, or to pick up depending on context.

In this sentence, preuzimanje means the action or process of collecting / picking up baggage.

Grammatically, it behaves like a singular neuter noun, which is important because the verb agrees with it:

• preuzimanje = singular
• so the verb is počinje = begins / is beginning

Because preuzimanje is a noun, not a normal finite verb.

In Croatian, when an action is expressed as a noun, the thing affected by that action is often put in the genitive:

• preuzimanje prtljage = the pickup/collection of baggage

If you used a verb instead, you would normally use the accusative:

• Preuzimamo prtljagu = We are collecting the baggage

So:

• prtljage = genitive, after the verbal noun preuzimanje
• prtljagu = accusative, after a regular verb

Here it is genitive singular of prtljaga.

That can be confusing, because prtljage can also look like a plural form in other contexts. But in this sentence, the grammar shows that it is genitive singular, because it depends on preuzimanje.

Also, prtljaga often works like a mass / collective noun, similar to baggage or luggage in English. So even though English learners may expect a plural idea, Croatian often treats it as a singular noun.

Because the subject is preuzimanje, not prtljage.

The structure is:

• Preuzimanje = subject
• prtljage = dependent genitive, meaning of baggage
• počinje = verb agreeing with preuzimanje

So the sentence is literally structured like:

• The baggage pickup begins now

Since preuzimanje is singular, the verb must also be singular:

• počinje, not počinju

Because počinje is the present-tense form of the imperfective verb počinjati, while počne comes from the perfective verb početi.

In a sentence like this, počinje is the natural choice for something that is starting now as an event or process:

• Preuzimanje prtljage počinje sada = Baggage pickup begins now / is beginning now

By contrast, počne is usually used in different environments, often after words like kad:

• Kad preuzimanje prtljage počne... = When baggage pickup starts...

So for a straightforward announcement, počinje sounds normal.

Sada means now.

It tells you that the action is starting at this moment. In this sentence, it gives the sentence an announcement-like feel:

• Preuzimanje prtljage počinje sada = Baggage pickup begins now

Yes, you can also say sad, which is a shorter everyday form of sada. But:

• sada sounds more neutral or formal
• sad sounds more conversational

In announcements, instructions, or formal speech, sada is often preferred.

Croatian word order is fairly flexible.

The given order:

• Preuzimanje prtljage počinje sada

is perfectly natural and neutral.

But you could also say:

• Sada počinje preuzimanje prtljage
  This puts more emphasis on now.
• Počinje preuzimanje prtljage
  This is also very natural in announcement style.

So the meaning stays very similar, but the emphasis can shift depending on word order.

A few sounds here are especially important for English speakers:

• č in počinje sounds roughly like ch in church, but a bit firmer
• nj in počinje sounds like ny in canyon
• lj in prtljage sounds roughly like lli in million for many learners

So very roughly:

• počinje ≈ PO-chee-nye
• prtljage is harder because of the consonant cluster at the start: prt-lja-ge

That prt- cluster is normal in Croatian, even though it feels difficult to English speakers. Try not to insert a strong extra vowel before it.