Na pješačkom prijelazu ispred škole vozači uglavnom stanu čim vide djecu.

Because na can take different cases depending on meaning:

• na + locative = location, on / at
• na + accusative = motion toward something, onto / to

Here the meaning is location: the action happens at the pedestrian crossing, so Croatian uses the locative:

• na pješačkom prijelazu = at the pedestrian crossing

If there were movement toward it, you could get the accusative instead.

Also, both words change:

• pješački → pješačkom
• prijelaz → prijelazu

They must agree in case, number, and gender.

Pješački prijelaz is the standard Croatian term for a pedestrian crossing / crosswalk.

• pješak = pedestrian
• pješački = pedestrian, relating to pedestrians
• prijelaz = crossing

So literally it is something like pedestrian crossing.

Because ispred means in front of and it requires the genitive case.

So:

• škola = school
• ispred škole = in front of the school

This is a very common pattern in Croatian:

• ispred kuće = in front of the house
• ispred zgrade = in front of the building
• ispred škole = in front of the school

Vozači is nominative plural, because it is the subject of the sentence.

• singular: vozač = driver
• plural: vozači = drivers

The verb agrees with this plural subject:

• vozači ... stanu
• vozači ... vide

Both verbs are in 3rd person plural.

Uglavnom means mostly, generally, or for the most part.

In this sentence it tells you that this is the usual pattern, not an absolute rule:

• vozači uglavnom stanu = drivers usually / generally stop

It is an adverb, and its position is fairly flexible, although this placement sounds very natural.

Stanu is the 3rd person plural present form of stati.

Here stati means to stop / come to a halt.

So:

• stati = to stop
• stanu = they stop

In this sentence, stanu presents the action as a whole completed event: the drivers come to a stop when they see children.

Yes, but the nuance changes.

• stanu suggests they come to a stop
• staju sounds more like they are stopping / tend to stop

In this sentence, stanu is very natural because the idea is that each time the drivers see children, they actually stop. Croatian often uses this kind of form to describe repeated, complete events.

So vozači uglavnom stanu čim vide djecu sounds like:

• when this situation happens, the result is that they stop

If you used staju, the sentence would still be understandable, but it would feel a bit less crisp.

Čim means as soon as.

So:

• čim vide djecu = as soon as they see children

Compared with kad:

• kad = when
• čim = as soon as, immediately when

So čim is more specific and more immediate. It emphasizes that the stopping happens right after the drivers notice the children.

Because djecu is the direct object of vide, so it is in the accusative case.

• djeca = children
• vide djecu = they see children

This is the usual pattern:

• vidjeti nekoga / nešto = to see someone / something

So the object goes into the accusative.

Yes. Djeca is a very common irregular noun.

It means children, but it does not decline like a regular plural noun. In this sentence you see:

• nominative: djeca = children
• accusative: djecu = children

That is why the form may look surprising to an English speaker.

No, Croatian word order is fairly flexible.

The given sentence begins with the location phrase:

• Na pješačkom prijelazu ispred škole ...

This sets the scene first: at the crossing in front of the school.

You could also say:

• Vozači uglavnom stanu čim vide djecu na pješačkom prijelazu ispred škole.
• Čim vide djecu, vozači uglavnom stanu.

But the original order is natural because it highlights the setting before introducing what drivers do there.

Because Croatian does not have articles like English the and a/an.

So:

• škole can mean the school or a school
• djecu can mean the children or children

The exact meaning comes from context. In this sentence, English would naturally use the school and children, but Croatian does not need separate article words to express that.