Kad dođemo kući, objesit ću kaput na vješalicu.

Because after kad (when), Croatian normally uses a present-tense form to talk about a future event.

So:

• Kad dođemo kući = When we get home
• not usually Kad ćemo doći kući

This is especially common with perfective verbs, and doći / dođemo is perfective. English does something similar: we say When we get home, not When we will get home.

Here kad means when.

Kad and kada both mean when, but:

• kad is shorter and very common in everyday speech
• kada is a bit fuller and can sound slightly more formal or emphatic

In this sentence, kad is completely natural.

It is built into the verb dođemo.

The ending -mo tells you the subject is we. Croatian often leaves subject pronouns unstated because the verb ending already shows the person and number.

So:

• dođem = I come / I arrive
• dođeš = you come
• dođemo = we come

You could say Kad mi dođemo kući..., but mi is usually unnecessary unless you want emphasis.

Kući is a very common fixed form meaning home / to home after verbs of motion.

So Croatian often says:

• ići kući = to go home
• doći kući = to come home
• vratiti se kući = to return home

This is just one of those very frequent expressions you should learn as a chunk.

Compare:

• kući = homeward, to home
• kod kuće = at home

So in this sentence, Kad dođemo kući means when we get home.

This is how the Croatian future is commonly formed with the short form of htjeti (ću).

With many infinitives ending in -ti, when the clitic comes after the infinitive, the final -i drops:

• objesiti
  • ću → objesit ću
• raditi
  • ću → radit ću

So objesit ću is the normal future form here.

You can also put the clitic before the infinitive in some word orders:

• Ja ću objesiti kaput.

But in objesit ću kaput, the shortened form is expected.

Ću is the short form of the auxiliary verb htjeti (to want) used to make the future tense.

In the future tense, the short forms are:

• ću = I will
• ćeš = you will
• će = he/she/it will
• ćemo = we will
• ćete = you will
• će = they will

So:

• objesit ću = I will hang
• objesit ćemo = we will hang

It is in a different case: kaput here is accusative singular, because it is the direct object.

The reason it looks unchanged is that many masculine inanimate nouns have:

• nominative = accusative

So:

• kaput (nominative) = coat
• kaput (accusative) = coat

If it were a masculine animate noun, you would usually see a visible change.

Because Croatian uses different cases after na depending on whether there is movement toward a place or location in a place.

Here, the coat is being moved onto the hanger, so Croatian uses accusative:

• na vješalicu = onto the hanger

If you were describing where the coat already is, you would use locative:

• Kaput je na vješalici. = The coat is on the hanger.

So:

• motion/direction → na + accusative
• location → na + locative

Yes. The sentence uses perfective verbs:

• doći → dođemo
• objesiti → objesit ću

Perfective verbs present actions as single, complete events. That fits this sentence well, because the speaker means:

1. we will arrive home
2. I will hang up the coat

Both are seen as completed future actions.

If you used imperfective verbs instead, the meaning would shift toward process, repetition, or habit.

Because Kad dođemo kući is a subordinate clause placed before the main clause.

So the structure is:

• subordinate clause: Kad dođemo kući
• main clause: objesit ću kaput na vješalicu

Croatian normally separates them with a comma.

Yes, Croatian word order is flexible, but not completely free.

This sentence is natural as written:

• Kad dođemo kući, objesit ću kaput na vješalicu.

You could also say:

• Kaput ću objesiti na vješalicu kad dođemo kući.
• Kad dođemo kući, kaput ću objesiti na vješalicu.

The main thing to remember is that ću is a clitic, so it cannot normally stand alone at the beginning of its clause. That is why Croatian arranges words around it in special ways.

Vješalica can mean a hanger or a place/device for hanging things, depending on context.

In this sentence, with kaput, the natural meaning is something like:

• a coat hanger
• a hook or coat rack spot

The exact English word can vary a bit depending on what kind of hanging place you imagine, but the Croatian word itself is normal and natural here.