Learn Hardcore Croatian: Skiper provjerava jedro prije polaska. - The skipper checks the sail before departure.

Skiper means skipper, especially the person in charge of a boat or yacht. It is very common in nautical contexts in Croatian and comes from English.

Grammatically here, skiper is a masculine noun in the nominative singular, because it is the subject of the sentence.

Why is it provjerava? What form is that?

Provjerava is the 3rd person singular present tense of the verb provjeravati / provjeriti meaning to check.

So:

ja provjeravam = I check / I am checking
ti provjeravaš = you check
on/ona/ono provjerava = he/she/it checks

Here it matches skiper, which is he/she in grammatical agreement, so provjerava = checks / is checking.

Why does Croatian use provjerava instead of a separate form for is checking?