Večeras ću paziti na djecu dok roditelji rade.

In Croatian, ću is a clitic, which means it usually cannot stand in the very first position of the sentence. It tends to come in the second position.

So:

• Večeras ću paziti na djecu. = natural
• Ja ću večeras paziti na djecu. = also natural

But starting directly with ću would not work in a normal sentence.

This is a very common pattern in Croatian word order:

• Sutra ću doći.
• On će raditi.
• Danas ćemo ostati kod kuće.

This is the future I tense in Croatian.

It is formed with:

• the clitic form of htjeti (ću, ćeš, će, ćemo, ćete, će)
• plus the infinitive of the main verb

Here:

• ću = I will
• paziti = infinitive, to look after / to watch

So:

• pazit ću or ću paziti = I will look after

Both are possible, but the placement depends on word order:

• Ja ću paziti...
• Pazit ću...

The verb paziti often goes with na + accusative when it means to watch / look after / keep an eye on someone or something.

So:

• paziti na dijete = to look after a child
• paziti na djecu = to look after the children

This is just the normal pattern of the verb in this meaning. You should learn it as a unit:

• paziti na nekoga
• paziti na nešto

Also note that paziti can have slightly different meanings depending on context:

• Pazi! = Watch out! / Be careful!
• Pazim na djecu. = I am looking after the children.
• Pazim na prehranu. = I watch what I eat / I pay attention to my diet.

Because djecu is the accusative plural form, and it is the object of paziti na.

The noun djeca means children, but it behaves a bit irregularly.

Important forms:

• djeca = nominative plural
• djece = genitive
• djecu = accusative

So:

• Djeca rade. = The children are working.
  (subject = nominative)
• Vidim djecu. = I see the children.
  (direct object = accusative)
• Pazim na djecu. = I look after the children.
  (na here requires the accusative)

This is a form learners usually just have to memorize.

Roditelji is nominative plural, because it is the subject of rade.

So in the clause:

• roditelji rade = the parents are working

Here:

• roditelji = the parents
• rade = work / are working

Since they are the ones doing the action, nominative is used.

This is very normal in Croatian.

After dok meaning while, Croatian often uses the present tense in the subordinate clause, even when the whole situation refers to the future.

So:

• Večeras ću paziti na djecu dok roditelji rade.

literally looks like:

• Tonight I will look after the children while the parents work/are working.

In English, we also often do something similar:

• I’ll stay here while you work.

So the main clause is in the future:

• ću paziti

And the time clause with dok stays in the present:

• roditelji rade

Here dok means while.

It introduces a time clause:

• dok roditelji rade = while the parents are working

Depending on context, dok can also sometimes mean until, but in this sentence it clearly means while because both actions happen at the same time:

• I will look after the children
• while the parents work

So this is a simultaneous action meaning.

Yes, very often you could.

• Večeras ću čuvati djecu.
• Večeras ću paziti na djecu.

Both can mean I’ll look after the children tonight.

There can be a small nuance:

• čuvati djecu often sounds like babysit / take care of
• paziti na djecu often sounds like watch / keep an eye on / supervise

In many everyday situations, they overlap a lot, and either one may sound natural.

Croatian word order is fairly flexible, but some versions sound more natural than others.

Natural options include:

• Večeras ću paziti na djecu dok roditelji rade.
• Ja ću večeras paziti na djecu dok roditelji rade.
• Pazit ću na djecu večeras dok roditelji rade.

The version you have is very natural because it starts with the time expression Večeras, then places the clitic ću in second position.

So yes, word order can change, but clitics like ću still follow special placement rules.

Croatian does not have articles like a and the.

So nouns appear without articles:

• djeca = children / the children
• roditelji = parents / the parents

The exact meaning is understood from context.

In this sentence, the context makes it clear that we mean specific children and specific parents, so English uses the, but Croatian does not need any equivalent word.

These forms can be tricky for English speakers.

• ću sounds roughly like chu in chew, but shorter and lighter.
• djecu is roughly djetsu or dye-tsu, depending on how you hear it, though the exact Croatian sound is not identical to English sounds.

A rough breakdown:

• dje in djecu starts with a soft dj sound
• cu here sounds like tsu

So:

• djecu ≈ DJE-tsu

This is only an approximation, but it helps as a starting point.

Yes. In many contexts, večeras can be translated as either this evening or tonight.

Examples:

• Vidimo se večeras. = See you tonight / this evening.
• Večeras ću ostati kod kuće. = I’ll stay home tonight.

The exact English translation depends on context and style, but the Croatian word itself is perfectly normal in both senses.