Kad djeca zaspu, uvijek utišavam glazbu, a ponekad je potpuno ugasim ako je netko prije toga previše pojačao.

Zaspu is the 3rd person plural present of the verb zaspati, which means to fall asleep.

So:

• dijete zaspi = the child falls asleep
• djeca zaspu = the children fall asleep

Here that is the right verb because the idea is when the children fall asleep, not simply when they are sleeping.

Because spavati and zaspati are different:

• spavati = to sleep / be asleep
• zaspati = to fall asleep

So:

• kad djeca spavaju = when the children are sleeping
• kad djeca zaspu = when the children fall asleep

This sentence focuses on the moment after they doze off, so zaspu is the better choice.

Croatian does not have articles like the or a/an. Whether something is definite or indefinite is understood from context.

So djeca can mean children or the children, and glazbu can mean music or the music, depending on the situation.

Because glazbu is the accusative singular form of glazba.

• glazba = nominative form
• glazbu = accusative form

It is accusative here because it is the direct object of the verb:

• utišavam glazbu = I turn down the music

The same object is understood later with ugasim as well.

They all relate to sound/volume, but they describe different actions:

• utišavam = I turn down / lower / quieten
• ugasim = I turn off / switch off
• pojačao = turned up / increased the volume

So the sentence describes this sequence:

1. someone turned the music up too much
2. when the children fall asleep, I usually turn it down
3. sometimes I switch it off completely

This is mainly about aspect.

• utišavam is imperfective
• ugasim is perfective

In this sentence, utišavam fits a habitual action with uvijek: I always turn the music down. It presents the action as a regular repeated activity.

Ugasim presents the action as reaching a clear endpoint: the music ends up off. Even though it happens only sometimes, each individual action is complete.

So the contrast is natural:

• utišavam = repeated action of lowering the volume
• ugasim = complete act of switching it off

Here je means it. It refers back to glazbu.

Croatian often avoids repeating the full noun once it is already clear:

• utišavam glazbu
• ponekad je potpuno ugasim = sometimes I turn it off completely

This je is a short unstressed pronoun, called a clitic, so it usually appears very early in the clause.

Because clitic pronouns in Croatian normally go in second position in the clause.

So in:

• ponekad je potpuno ugasim

the first element is ponekad, and the clitic je comes right after it.

That word order sounds natural in Croatian. English speakers often want to place the pronoun later, but Croatian usually pulls these short forms forward.

No. It looks the same, but it is doing a different job.

• In ponekad je potpuno ugasim, je = it
• In ako je netko prije toga previše pojačao, je is the auxiliary verb to be, used to form the past tense

So:

• je pojačao = has turned up / turned up

Because netko is grammatically treated as masculine singular by default.

So Croatian normally says:

• netko je došao
• netko je rekao
• netko je pojačao

This does not necessarily mean the person is male. It is just the default grammatical agreement pattern.

Because that action happened earlier than the action in the main part of the sentence.

The timeline is:

1. someone turned the music up too much
2. later, when the children fall asleep, I turn it down or switch it off

That is why Croatian uses the past form je ... pojačao, especially together with prije toga = before that / beforehand.

The object is omitted because it is obvious from context. It means turned it up or turned the music up.

Croatian often leaves out an object when it can be easily understood from what was already mentioned. Here the listener already knows the sentence is about glazba and its volume.

Here a links the two clauses and adds a slight contrast or shift.

It is something like:

• and
• while
• but

depending on context.

In this sentence:

• uvijek utišavam glazbu = I always turn the music down
• a ponekad je potpuno ugasim = and/but sometimes I turn it off completely

It is softer and less strongly contrastive than ali.

Yes, ugasim already means I turn it off, but potpuno adds emphasis: completely, entirely, all the way.

It helps highlight the contrast between:

• utišavam = I lower the volume
• potpuno ugasim = I shut it off completely

So potpuno is not strictly necessary, but it makes the meaning stronger and clearer.

Literally, prije toga means before that.

In smoother English here, it can be:

• beforehand
• earlier
• prior to that

So:

• ako je netko prije toga previše pojačao
  means
• if someone had turned it up too much beforehand / earlier