Radna pauza počinje sada.

Because radna is the form of the adjective that agrees with pauza.

• pauza is feminine singular
• Croatian adjectives must match the noun in gender, number, and case

So:

• masculine: radni
• feminine: radna
• neuter: radno

Since pauza is feminine, you say radna pauza.

It is in the nominative singular.

In this sentence, radna pauza is the subject of the verb počinje, so nominative is the expected case.

You can think of the structure as:

• radna pauza = the subject
• počinje = starts / is starting
• sada = now

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

So radna pauza can mean:

• the work break
• a work break

Which one is meant depends on context. In this sentence, English would usually translate it as the break or the work break, but Croatian does not need a separate word for that.

Počinje is 3rd person singular present tense.

It matches the singular subject radna pauza.

So the pattern is:

• ja počinjem = I start / am starting
• ti počinješ = you start
• on/ona/ono počinje = he/she/it starts

Here, radna pauza is grammatically like ona because pauza is feminine singular, so počinje is the correct verb form.

This is about aspect, which is very important in Croatian.

Croatian often has verb pairs:

• počinjati = imperfective
• početi = perfective

Počinje comes from počinjati and is very natural for something that is starting now or for an announcement like this.

Počne comes from početi. Perfective present forms in Croatian often do not work exactly like simple present in English. They can sound more like a future or one-time completed event, depending on context.

So for a neutral announcement such as The break starts now, počinje sada is the expected choice.

Yes. Sada means now, and sad is a very common shorter form.

So these are both natural:

• Radna pauza počinje sada.
• Radna pauza počinje sad.

The version with sada can sound a little more neutral or slightly more formal, while sad is very common in everyday speech.

No, Croatian word order is fairly flexible.

Radna pauza počinje sada is a normal, neutral sentence, but you could also hear:

• Sada počinje radna pauza.
• Počinje radna pauza sada. — possible, but less neutral
• Radna pauza sada počinje. — also possible, with a slightly different emphasis

Changing the word order usually changes focus or emphasis, not the basic meaning.

Yes, absolutely.

If it is already clear which break you mean, pauza alone is enough:

• Pauza počinje sada. = The break starts now.

Adding radna makes it more specific: work break, break period at work, or simply a more formal announcement.

A rough pronunciation guide is:

po-chi-nye

A few key sounds:

• č sounds like ch in chocolate
• nj is a single sound, like ny in canyon

So počinje is not pronounced as separate n + j sounds in English style. The nj is blended.

Because Croatian usually does not need a separate subject pronoun when the subject is already stated.

Here, the subject is explicitly given as radna pauza, so adding a pronoun would be unnecessary.

Croatian often omits subject pronouns even when there is no noun, because the verb ending already gives information about the subject. In this sentence, though, the noun phrase radna pauza already does that job.