Projekcija počinje večeras.

In this sentence, projekcija usually means a screening or showing of a film.

Although the literal cognate is projection, Croatian projekcija is often used for a movie screening in contexts like cinemas, festivals, or events.

So in: Projekcija počinje večeras.

the most natural sense is:

• The screening starts tonight.
• The showing begins this evening.

Depending on context, projekcija can also mean projection in a technical or visual sense, but here screening is the likely interpretation.

Počinje is the 3rd person singular present tense form of počinjati / početi (to begin, to start).

The subject is projekcija, which is:

• singular
• feminine

So the verb must also be singular:

• projekcija počinje = the screening starts

If the subject were plural, you would use počinju:

• Projekcije počinju večeras. = The screenings start tonight.

In the present tense, Croatian verbs mainly agree with the subject in person and number, not in gender.

So počinje is used because projekcija is singular, not because it is feminine.

Gender becomes more visible in some other forms, especially the past tense:

• Projekcija je počela. = feminine singular
• Film je počeo. = masculine singular
• Predstava je počela. = feminine singular

So in your sentence, the important thing is that projekcija is singular, which gives počinje.

Večeras means tonight or this evening, depending on context.

It refers specifically to this evening / tonight, not evenings in general.

Compare:

• večeras = tonight / this evening
• svake večeri = every evening
• u večernjim satima = in the evening hours

So: Projekcija počinje večeras. means the event starts tonight, not simply in the evening as a general habit.

Because večeras is a fixed adverb meaning tonight / this evening.

Croatian has several time expressions like this:

• danas = today
• sutra = tomorrow
• jutros = this morning
• večeras = tonight / this evening

So you do not split it into separate words in normal usage.

Croatian does not have definite or indefinite articles like English the and a/an.

So:

• projekcija can mean a screening or the screening
• the exact meaning depends on context

In this sentence, English might naturally use:

• The screening starts tonight. or
• A screening starts tonight.

Croatian does not need an article to express that.

Here projekcija is in the nominative singular because it is the subject of the sentence.

The basic dictionary form is also projekcija.

You can tell it is the subject because it is the thing that starts:

• Projekcija počinje večeras.

If it were in another role, the form could change. For example:

• Čekamo projekciju. = We are waiting for the screening.
  Here projekciju is accusative singular.

Yes, but with some differences.

• Projekcija započinje večeras is possible and means almost the same thing.
  započinjati / započeti can sound a bit more formal or emphatic than počinjati / početi.

• Projekcija počne večeras is generally not the normal choice in a plain present-tense statement like this.

For a simple statement about something scheduled, počinje is the natural form.

So the safest standard version is:

• Projekcija počinje večeras.

It usually refers to a scheduled future event.

Croatian, like many languages, often uses the present tense for planned or scheduled future events.

So: Projekcija počinje večeras. means:

• The screening starts tonight.

This is very similar to English:

• The movie starts tonight
• My train leaves tomorrow

So even though the verb is present tense, the meaning is often future because of the time expression večeras.

Yes. Croatian word order is more flexible than English, although the neutral order here is very natural:

• Projekcija počinje večeras.

Other orders are possible, especially for emphasis:

• Večeras projekcija počinje.
• Večeras počinje projekcija.

These may sound more marked or stylistically different depending on context.

The original version is the most straightforward and neutral if you are simply giving information.

A rough pronunciation is:

• počinje ≈ PO-chee-nye

More precisely:

• č sounds like ch in chocolate
• nj sounds like the ny in canyon
• the stress is typically on the first syllable: PÒčinje

So:

• projekcija ≈ pro-YEK-tsee-ya
• počinje ≈ PO-chee-nye
• večeras ≈ VE-che-ras

Exact stress can vary in teaching materials, but that approximation will be understood well.

Yes, projekcija is a feminine noun.

A very common clue in Croatian is that nouns ending in -a are often feminine:

• projekcija
• večera
• škola
• predstava

There are exceptions, but this is a useful general rule.

You can also see its feminine behavior in other forms, for example in the past tense:

• Projekcija je počela.

The ending -la in počela matches a feminine singular subject.