Kućna adresa je potrebna; u protivnom dostava je nemoguća.

It means home address or residential address.

• kućna = home / domestic / household, from kuća = house, home
• adresa = address

In this sentence, it refers to the address where the person lives.

Because Serbian does not have articles.

So kućna adresa can mean:

• a home address
• the home address
• simply home address

The exact meaning depends on context.

Because adresa is a feminine singular noun, and the adjective has to agree with it.

Here are the forms of potreban:

• masculine: potreban
• feminine: potrebna
• neuter: potrebno

So:

• adresa je potrebna = the address is necessary / required

It is in the nominative singular.

That is because it is the subject of the clause:

• Kućna adresa je potrebna = A home address is required

Both words are nominative feminine singular:

• kućna
• adresa

Literally, it means is necessary.

But in practical English, especially on forms or notices, it is often best translated as:

• is required
• is needed

So Kućna adresa je potrebna is a very natural Serbian way to say A home address is required.

It means otherwise or if not.

This is a common fixed expression, especially in formal or written Serbian.

So:

• u protivnom dostava je nemoguća = otherwise, delivery is impossible

Because this expression is really a shortened form of:

• u protivnom slučaju = in the opposite case / otherwise

Here, protivnom matches the omitted noun slučaju.

So even when slučaju is left out, Serbian still keeps:

• u protivnom

This is just the normal fixed phrase.

Dostava means delivery.

In this sentence, it refers to the delivery of goods, mail, or an order.

So:

• dostava je nemoguća = delivery is impossible

Again, because dostava is feminine singular.

The adjective must agree with the noun:

• masculine: nemoguć
• feminine: nemoguća
• neuter: nemoguće

So:

• dostava je nemoguća = delivery is impossible

Yes. That is also correct.

These are both possible:

• dostava je nemoguća
• dostava nije moguća

They mean almost the same thing.
Je nemoguća sounds a bit more compact and formal, which fits this sentence well.

Not completely. Serbian word order is fairly flexible.

This version:

• Kućna adresa je potrebna; u protivnom dostava je nemoguća.

sounds natural and formal.

Other possible wordings include:

• Kućna adresa je potrebna; dostava je u protivnom nemoguća.
• Bez kućne adrese dostava je nemoguća.

The original order is good because it clearly sets up the condition first, then the consequence.

The semicolon links two closely related independent clauses:

• Kućna adresa je potrebna
• u protivnom dostava je nemoguća

It gives the sentence a formal, administrative tone. That suits messages on forms, websites, or delivery notices.

Yes, definitely. It sounds like something you would read on:

• an online order form
• a delivery policy
• an official notice

A more conversational version might be:

• Treba nam kućna adresa, inače ne možemo da izvršimo dostavu.
• Bez kućne adrese ne možemo da dostavimo pošiljku.

So the original is correct and natural, but clearly formal.

The letter ć is a soft ch-like sound.

English speakers often compare it loosely to ch, but it is softer than the ch in chair.

A rough approximation of kućna is:

• kooch-na

But remember that this is only approximate. Also, Serbian distinguishes:

• ć = softer
• č = harder

That difference matters in pronunciation, even if it can be difficult at first for English speakers.