Kamera prati pokret kamiona.

Here prati is the 3rd-person singular present tense of pratiti, meaning follows, tracks, or monitors.

It agrees with the singular subject kamera:

• ja pratim = I follow
• ti pratiš = you follow
• on/ona/ono prati = he/she/it follows

A useful warning: prati can also be the infinitive of a different verb meaning to wash. In this sentence, though, it is clearly the present-tense form of pratiti.

Because pokret is the direct object of prati, it is in the accusative singular.

The noun pokret is masculine inanimate, and for masculine inanimate nouns, the accusative singular looks the same as the nominative singular. So:

• nominative: pokret
• accusative: pokret

That is why the form does not change here.

Kamiona is in the genitive. It depends on pokret and means of the truck.

So:

• pokret = movement
• pokret kamiona = movement of the truck

Croatian often uses the genitive after a noun where English would use of.

In form, kamiona can be ambiguous. It can be:

• genitive singular: of the truck
• genitive plural: of trucks

In this sentence, the intended meaning is singular. Usually context tells you which meaning is meant.

Croatian does not have articles. So kamera can mean a camera or the camera, depending on context. The same applies to the rest of the sentence.

English learners often expect a separate word for the, but Croatian simply does not use one.

Yes. Croatian word order is fairly flexible because case endings show what each noun is doing.

The version here:

Kamera prati pokret kamiona.

is the most neutral way to say it.

You could also say:

Pokret kamiona prati kamera.

That would still be grammatical, but it would give more emphasis to pokret kamiona.

Not exactly.

• Kamera prati kamion. = The camera follows the truck.
• Kamera prati pokret kamiona. = The camera follows the truck's movement.

The second version focuses more specifically on the motion or movement, not just on the truck as an object.

Yes. Pratiti is an imperfective verb, so it usually describes an ongoing, repeated, or continuous action.

That fits this sentence well, because tracking a truck's movement is normally something continuous, not a single finished event.

So prati here suggests something like:

• is following
• is tracking
• follows regularly

rather than one single completed action.