Ovlašteni servis provjerava program pranja, bubanj i filtar.

Because ovlašteni is an adjective and it has to agree with servis.

• servis is masculine
• singular
• nominative case, because it is the subject of the sentence

So the adjective also appears in the masculine singular nominative form: ovlašteni.

If the noun changed, the adjective would change too:

• ovlaštena tvrtka = an authorized company
• ovlašteno mjesto = an authorized place
• ovlašteni servisi = authorized service centers

It means an authorized service center, authorized repair service, or officially approved service provider.

A learner may first think servis only means service, but in Croatian it often means:

• a repair shop
• a maintenance center
• a service department

So ovlašteni servis is a very common phrase for an official repair/service center, especially for appliances, cars, and electronics.

Provjerava is the present tense, 3rd person singular, from the verb provjeravati / provjeriti.

Here it means:

• checks
• is checking
• sometimes does check, depending on context

Because Croatian present tense can cover both a general/habitual meaning and a current action, the exact English translation depends on the situation.

In this sentence, it most naturally means something like The authorized service center checks...

That is just how this verb is conjugated.

The verb is provjeravati / provjeriti and the present-tense form for he/she/it is provjerava.

A few present forms are:

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

So servis provjerava = the service center checks.

Yes, they are direct objects, so they are in the accusative case. But for masculine inanimate nouns, the accusative singular is usually the same as the nominative singular.

That is why you see:

• program
• bubanj
• filtar

with no visible change here.

This is very normal in Croatian:

• Vidim stol. = I see the table.
• Kupujem auto. = I am buying a car.

Both stol and auto are objects, but their forms do not change visibly.

Because pranja is the genitive singular of pranje.

So program pranja literally means program of washing, which English would normally express as washing program or wash program.

This is a very common Croatian structure:

• vrijeme ručka = lunch time
• boja zida = the color of the wall
• program pranja = washing program

So pranja is not a verb here. It is a noun form connected to prati / pranje.

In this sentence, it is functioning as a noun.

The base form is pranje, a verbal noun meaning washing. Croatian often uses these verbal nouns where English also uses nouns ending in -ing.

So:

• pranje = washing
• program pranja = washing program

Even though it comes from a verb, here it behaves like a noun and changes by case:

• pranje
• pranja
• pranju and so on.

Because the sentence is listing three things being checked:

• program pranja
• bubanj
• filtar

Croatian punctuation works similarly to English here:

• commas separate items in a list
• usually there is no comma before i = and

So:

• program pranja, bubanj i filtar

is the normal Croatian way to write the washing program, the drum, and the filter.

No, Croatian word order is fairly flexible, but this sentence uses a very natural, neutral order:

• Ovlašteni servis = subject
• provjerava = verb
• program pranja, bubanj i filtar = objects

That is the clearest and most standard order for an informational sentence.

Other word orders are possible for emphasis, for example:

• Program pranja, bubanj i filtar provjerava ovlašteni servis.

This still means the same thing, but it sounds more marked or more formal, because it emphasizes what is being checked.

It can mean either, depending on context.

In sentences like this, servis often refers to the service center as an institution/business, not one individual person. English does something similar:

• The hospital says...
• The company checks...

So servis provjerava does not mean the building itself is doing something. It means the authorized service center, or the staff working there, performs the check.

Because the verb agrees with the subject, not with the objects.

The subject is ovlašteni servis, which is singular, so the verb is singular too:

• servis provjerava = the service center checks

The things being checked are objects:

• program pranja
• bubanj
• filtar

Even though there are three of them, they do not control the verb form.