Danas imam sastanak koji počinje u šest sati.

In Serbian, the subject pronoun is often omitted because the verb already shows who is doing the action.

• imam = I have
• The ending -m tells you the subject is I

So Danas imam sastanak naturally means Today I have a meeting.
You could say Ja danas imam sastanak, but ja is usually added only for emphasis or contrast.

Danas means today.

It does not have to come first, although putting it first is very natural. Serbian word order is more flexible than English word order.

For example, all of these are possible:

• Danas imam sastanak.
• Imam danas sastanak.
• Imam sastanak danas.

They all mean roughly the same thing, but the first one is the most neutral and common here.

Yes. Serbian commonly uses imati (to have) in this kind of sentence, just like English.

• imam sastanak = I have a meeting
• imam čas = I have a class
• imam ispit = I have an exam

So this is a very normal way to express that something is scheduled for you.

Sastanak is in the accusative singular, because it is the direct object of imam.

However, sastanak is a masculine noun that refers to a non-living thing, and for many masculine inanimate nouns, the accusative singular looks the same as the nominative singular.

So:

• nominative: sastanak
• accusative: sastanak

That is why the form does not change here.

Koji means which or that in this sentence. It introduces a relative clause:

• sastanak koji počinje u šest sati
• the meeting that starts at six o’clock

So koji počinje u šest sati gives extra information about sastanak.

Because koji must agree with the noun it refers to.

It refers to sastanak, which is:

• masculine
• singular
• here functioning as the subject of the relative clause

So the correct form is koji.

Compare:

• sastanak koji... = meeting that...
• knjiga koja... = book that...
• pismo koje... = letter that...

Because the verb počinje belongs to sastanak, not to I.

The structure is:

• imam sastanak = I have a meeting
• koji počinje u šest sati = which starts at six o’clock

So the thing that starts is the meeting, and sastanak is third person singular. That is why Serbian uses:

• počinje = starts / begins

not

• počinjem = I start / I am starting

The basic dictionary form is počinjati or početi, depending on whether you are looking at the imperfective or perfective verb.

Here are the important points:

• počinje is from počinjati (imperfective)
• It means starts / is starting / begins
• In schedule-type statements, Serbian often uses the present tense for future meaning, just like English can do in The meeting starts at six

So koji počinje u šest sati is a normal way to describe a scheduled future event.

The preposition u is used here to mean at when talking about clock time.

So:

• u šest sati = at six o’clock
• u pet sati = at five o’clock
• u osam sati = at eight o’clock

This is the normal Serbian pattern for saying when something happens.

Both can occur, but u šest sati is a full, clear way to say at six o’clock.

Literally, sati is related to hours, but in this expression the whole phrase means a clock time, not a duration.

So:

• u šest = at six
• u šest sati = at six o’clock

The version with sati can sound slightly more explicit or formal depending on context.

After numbers like pet, šest, sedam and higher, Serbian uses a special number phrase where the noun often appears in a form like sati.

Examples:

• pet sati = five o’clock / five hours
• šest sati = six o’clock / six hours
• sedam sati = seven o’clock / seven hours

So u šest sati is the expected form.

In this sentence, it clearly means at six o’clock because of the preposition u, which marks a point in time.

• u šest sati = at six o’clock
• šest sati by itself can also mean six hours, depending on context

For example:

• Sastanak počinje u šest sati. = The meeting starts at six o’clock.
• Sastanak traje šest sati. = The meeting lasts six hours.

Yes. In this sentence, English could say either:

• the meeting which starts at six
• the meeting that starts at six

In natural English, that is often more common in everyday speech, but Serbian uses koji as the normal relative pronoun here.

Yes. Serbian often uses the present tense for scheduled future events, especially in relative clauses and time-related statements.

So although:

• imam is present
• počinje is present

the meaning is future because the context is about today’s schedule.

This is similar to English:

• Today I have a meeting that starts at six.

English also uses present tense here for a planned future event.

Yes, but it changes the feel slightly.

• koji počinje u šest sati = that starts at six o’clock
• koji će početi u šest sati = that will start at six o’clock

The version with počinje is very natural for schedules and timetables.
The version with će početi is also grammatical, but often sounds a bit more explicitly future-oriented.

So the original sentence is completely normal and idiomatic.

Serbian can shift word order or add stress for emphasis.

For example:

• Danas imam sastanak koji počinje u šest sati.
  Neutral: Today I have a meeting that starts at six.

• Ja danas imam sastanak koji počinje u šest sati.
  Emphasizes I.

• Danas imam sastanak koji počinje u šest sati, ne sutra.
  Emphasizes today, not tomorrow.

• Danas imam sastanak koji počinje u šest sati, a ne u sedam.
  Emphasizes the time.

So the original version is neutral, but Serbian allows flexible emphasis through word order and stress.