Questions & Answers about Film počinje u sedam sati, ali se završava kasno.
Serbian does not have articles like the or a/an.
So film can mean the film, a film, or just film, depending on context. In this sentence, context tells you it means the film.
- Film počinje... = The film starts...
Because Serbian often uses the present tense for scheduled events, just like English does.
Compare English:
- The film starts at seven.
- The train leaves at six.
Serbian does the same:
- Film počinje u sedam sati.
So this is a normal way to talk about a timetable or fixed schedule.
Počinje is the present-tense form of the imperfective verb počinjati / počinjati se? No—here the relevant basic pair is:
- počinjati = to be starting / to start (imperfective)
- početi = to start, to begin (perfective)
In everyday Serbian, počinje is the natural form in a sentence like this because it describes a scheduled event.