Večera počinje u osam sati.

Večera is the subject of the sentence, so it is in the nominative singular.

It is the noun večera, meaning dinner / supper.
Because it is a feminine noun ending in -a, its nominative singular form is večera.

A useful comparison:

• večera = nominative, dinner as the subject
• večeru = accusative, used when dinner is the object

So here, Večera počinje... literally means Dinner begins...

It can actually be both, which can confuse learners.

• večera as a noun = dinner
• večera as a verb form = he/she is having dinner from večerati

In this sentence, though, it is clearly a noun, because the main verb is počinje.

So the structure is:

• večera = subject
• počinje = verb

Serbian often uses the present form for events that are scheduled or expected, especially when the time is clearly stated.

So Večera počinje u osam sati is very natural for:

• a planned event
• a scheduled start time
• something like Dinner starts at eight

This is similar to English, where we also say:

• The movie starts at 8
• Class begins at 9

Serbian can also use an explicit future form:

• Večera će početi u osam sati.

That is also correct, but počinje sounds very natural for a scheduled event.

The dictionary form is početi, meaning to begin / to start.

Počinje means:

• it begins
• it is beginning
• in context, often it starts

In this sentence, the subject večera is grammatically singular, so the verb is in 3rd person singular:

• večera počinje = dinner begins / starts

In Serbian, u is the normal preposition used for clock times.

So:

• u osam = at eight
• u osam sati = at eight o’clock

This is just the standard pattern for saying when something happens at a specific hour.

Because Serbian changes the noun after numbers.

With sat (hour / o’clock), the pattern is:

• jedan sat
• dva / tri / četiri sata
• pet, šest, sedam, osam... sati

Since osam is 8, Serbian uses sati.

So:

• u jedan sat
• u dva sata
• u osam sati

This is a very important number pattern to learn.

Yes. In everyday speech, u osam is very common and completely natural.

So both are possible:

• Večera počinje u osam.
• Večera počinje u osam sati.

The version with sati is a little fuller and sometimes slightly more formal or explicit, but both are correct.

Yes. Serbian word order is fairly flexible.

The neutral order here is:

• Večera počinje u osam sati.

But you can also say:

• U osam sati večera počinje.
• Večera u osam sati počinje.

These alternatives may shift the emphasis slightly:

• starting with u osam sati emphasizes the time
• starting with večera is a neutral statement about dinner

So the original sentence is natural, but it is not the only possible order.

A learner may especially notice č and nj.

Roughly:

• po-či-nje

A few pronunciation points:

• č sounds like the ch in church, but a bit firmer
• nj is a single sound, like the ny in canyon
• Serbian stress is not usually marked in normal writing, so learners often just imitate native audio at first

So počinje sounds approximately like PO-chee-nye.

Usually večera is translated as dinner or supper, depending on the speaker and the variety of English.

In Serbian, it simply means the evening meal.

So the exact English word can vary, but the Serbian word itself is straightforward: večera = the meal eaten in the evening.

Yes, and it is grammatical, but the meaning is slightly different.

• Večera počinje u osam sati. = Dinner starts at eight.
• Večera je u osam sati. = Dinner is at eight.

The first one focuses on the start of the event.
The second one just states the time of the event more generally.

So they are close, but not identical.