Kad je vrijeme lijepo, moj otac sluša radio na balkonu.

Yes. Kad means when in this sentence.

The clause Kad je vrijeme lijepo means when the weather is nice. It introduces the condition or situation in which the main action happens.

You may also see kada, which is a slightly longer form of kad. In many everyday contexts, they are interchangeable:

• Kad je vrijeme lijepo...
• Kada je vrijeme lijepo...

Both are natural.

The comma separates the introductory subordinate clause from the main clause.

So the sentence is divided like this:

• Kad je vrijeme lijepo, = subordinate clause
• moj otac sluša radio na balkonu. = main clause

This is very similar to English:

• When the weather is nice, my father listens to the radio on the balcony.

In Croatian, putting a comma here is standard.

Both are possible, but they do slightly different jobs.

• lijepo vrijeme = nice weather
  This is a noun phrase.
• vrijeme je lijepo = the weather is nice
  This is a full clause with the verb to be.

In your sentence, we need a full clause after kad, so Croatian uses:

• Kad je vrijeme lijepo = When the weather is nice

The adjective lijepo is not directly attached to the noun as part of a phrase here; it is the predicate adjective, linked by je.

Because it agrees with vrijeme, which is neuter singular.

In Croatian, adjectives must agree with the noun in gender, number, and case.

• lijep = masculine singular
• lijepa = feminine singular
• lijepo = neuter singular

Since vrijeme is a neuter noun, the correct form is lijepo:

• vrijeme je lijepo

Because moj otac is the subject of the main clause, so it is in the nominative case.

• moj = my in masculine nominative singular
• otac = father in nominative singular

Together:

• moj otac = my father

If father had another role in the sentence, the form might change. But here he is the one doing the action, so nominative is required.

Sluša is the 3rd person singular present tense of the verb slušati, meaning to listen.

So:

• ja slušam = I listen
• ti slušaš = you listen
• on/ona sluša = he/she listens

Since the subject is moj otac (my father), Croatian uses sluša.

Not necessarily. In this sentence, the present tense expresses a habitual or general action.

So the meaning is closer to:

• When the weather is nice, my father listens to the radio on the balcony.

This describes what he typically does in that situation, not only what he is doing at this exact moment.

Croatian often uses the simple present in this kind of general statement, just like English does.

Because radio is the direct object of sluša, so it is in the accusative case. But for many inanimate masculine nouns, the accusative singular looks the same as the nominative singular.

So:

• nominative: radio
• accusative: radio

That is why the form does not change here.

A learner might expect a visible ending change, but with inanimate masculine nouns, that often does not happen in the singular.

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

So radio can mean:

• a radio
• the radio

The exact meaning depends on context.

This is very common in Croatian. You usually understand definiteness from the situation, not from a separate word.

Because na balkonu expresses location, not movement.

In Croatian, na can be used with different cases:

• na balkon = motion toward the balcony
• na balkonu = location on the balcony

Here the father is already there, listening, so Croatian uses the locative:

• na balkonu = on the balcony

If you wanted to say He goes onto the balcony, then you would use na balkon.

It is the locative singular of balkon.

The preposition na often takes:

• accusative for movement toward something
• locative for being at a place

So:

• na balkon = onto the balcony
• na balkonu = on the balcony

In this sentence, balkonu is locative because it answers where?

Yes. Croatian word order is more flexible than English word order, although some versions sound more natural than others depending on emphasis.

The original sentence is very natural:

• Kad je vrijeme lijepo, moj otac sluša radio na balkonu.

You could also say:

• Moj otac sluša radio na balkonu kad je vrijeme lijepo.

This still means essentially the same thing, but the focus feels slightly different. The first version highlights the condition first; the second starts with the subject.

So yes, word order can change, but it is not completely random. Different orders can sound more or less natural depending on emphasis and style.

Yes, many speakers would say that too.

• Kad je vrijeme lijepo
• Kad je lijepo vrijeme

Both are understandable and natural.

A small difference in feel:

• vrijeme je lijepo sounds like a standard clause: the weather is nice
• lijepo vrijeme is more like the noun phrase nice weather

In real usage, both patterns appear. For a learner, the important thing is that the sentence you were given is completely correct.

Yes. In Croatian, slušati takes a direct object, so you simply say:

• slušati radio
• literally: listen the radio

English needs to in listen to the radio, but Croatian does not use a preposition here.

This is a common difference between the two languages, and it is worth memorizing as a pattern:

• slušam glazbu = I listen to music
• sluša radio = he listens to the radio