Glavni izvođač je na tonskoj probi.

Glavni means main, principal, or headline depending on context.

Izvođač literally means performer, artist, or act. In a concert or festival context, glavni izvođač is the main performer or headlining act.

So this phrase does not have to refer to just one singer—it could also mean a band or another featured act.

Je is the 3rd person singular present of biti (to be), so it means is.

• Glavni izvođač je na tonskoj probi.
• The main performer is at the soundcheck.

In Croatian, the present tense of to be is usually stated explicitly in normal sentences, unlike in some other Slavic languages where it may be omitted.

Also, je is a clitic, which means it tends to appear in the second position of the sentence.

Croatian often uses na for being at an event, activity, or organized session.

So:

• na probi = at rehearsal
• na sastanku = at a meeting
• na koncertu = at a concert
• na predavanju = at a lecture

Using u would usually suggest being physically inside something, which is not the normal way to express this idea here. A soundcheck is treated as an event/activity, so na is the natural preposition.

It is in the locative singular.

The preposition na can take different cases depending on meaning:

• na + accusative = motion toward something
• na + locative = being at/on something

Here the sentence describes location/state, not movement:

• Glavni izvođač je na tonskoj probi.
• The main performer is at the soundcheck.

So we use the locative.

Because both the adjective and the noun must match the case, gender, and number required by the sentence.

The basic form is:

• tonska proba = soundcheck / literally sound rehearsal

This is feminine singular nominative.

After na in this sentence, we need the locative singular, so both words change:

• tonska → tonskoj
• proba → probi

So:

• na tonskoj probi = at the soundcheck

Yes, more or less.

Literally, tonska proba means something like sound rehearsal or audio rehearsal, but in real usage it corresponds to soundcheck.

You may also hear borrowed forms like soundcheck in informal speech, especially in music circles, but tonska proba is a normal and fully Croatian expression.

Yes. Izvođač can mean different things depending on context.

Common meanings include:

• performer / artist / act in music, theater, entertainment
• contractor / executor in technical or legal contexts

In this sentence, because of tonska proba (soundcheck), the meaning is clearly performer or main act.

Yes, Croatian word order is fairly flexible.

The neutral word order here is:

• Glavni izvođač je na tonskoj probi.

But you could also say:

• Na tonskoj probi je glavni izvođač.

That version puts more emphasis on where the main performer is.

One important detail: the clitic je still tends to stay near the beginning of the clause, in second position.

No. Croatian does not have articles like a or the.

So glavni izvođač can mean:

• the main performer
• sometimes just a main performer, depending on context

Usually the context makes it clear. In this sentence, English naturally uses the.

Yes, izvođač is a masculine noun.

If you specifically want to refer to a female performer, you can use:

• izvođačica = female performer

So you could say:

• Glavna izvođačica je na tonskoj probi.

Notice that the adjective also changes:

• glavni → glavna

to match the feminine noun.

A rough pronunciation guide is:

GLAHV-nee eez-VOH-djach yeh nah TOHN-skoy PROH-bee

A few useful sound notes:

• č sounds roughly like ch in church
• j sounds like y in yes
• lj, nj, dj/đ and similar combinations can take practice, but this sentence is fairly manageable

The stress can vary somewhat by region and speaker, but this guide will get you close enough to be understood.