Kolona auta stoji na cesti zbog gužve u prometu.

Because the grammatical subject is kolona (a line / queue / column), and kolona is singular.

So the structure is:

Kolona auta stoji
The line of cars is standing / is stopped

Even though there are many cars, Croatian makes the verb agree with kolona, not with auta.

If the subject were just auti or automobili, then you would use a plural verb: Auti stoje = The cars are standing / stopped

Here auta is genitive plural, meaning of cars.

So:

kolona auta = a line of cars

After nouns like kolona (line, queue, column), Croatian often uses the genitive to show what the line consists of.

A very literal breakdown is:

kolona = line
auta = of cars

A useful thing to notice is that with auto, the genitive plural auta looks the same as the nominative plural auta. The role is clear from the sentence structure.

Yes. Kolona automobila is completely correct.

The difference is mainly style:

• auto = everyday, shorter, very common
• automobil = more formal or fuller-sounding

So both work:

Kolona auta stoji na cesti.
Kolona automobila stoji na cesti.

Yes, literally stajati / stoji means to stand. But in traffic contexts, it often means:

• to be stopped
• to be at a standstill
• to not be moving

So Kolona auta stoji is a very natural way to say that the line of cars is not moving.

English often prefers is stopped or is at a standstill, while Croatian naturally uses stoji.

Because na cesti expresses location: on the road.

With na, Croatian usually works like this:

• na + accusative = movement onto/toward something
• na + locative = being on something

Here the cars are already there, not moving onto the road, so we use the locative:

• na cesti = on the road
• na cestu = onto the road

The noun is:

• cesta = road
• cesti = locative singular

Because zbog (because of) requires the genitive case.

So:

• gužva = crowd, congestion, jam
• gužve = genitive singular

That is why you get:

zbog gužve = because of the congestion / because of the jam

This is a very useful rule to remember: zbog + genitive

It means traffic congestion, heavy traffic, or a traffic jam.

Word by word:

• gužva = crowding, crush, congestion
• u prometu = in traffic

So literally it is something like congestion in traffic.

This is a common Croatian way to express the idea. English usually uses a more fixed expression like traffic jam.

Yes, absolutely.

Both are natural:

• gužva u prometu
• prometna gužva

They mean basically the same thing: traffic congestion / traffic jam.

A learner can think of them like this:

• gužva u prometu = congestion in traffic
• prometna gužva = traffic congestion

Both are good Croatian.

Here u means in, and it expresses location or situation, so it takes the locative case.

The noun is:

• promet = traffic
• prometu = locative singular

So:

u prometu = in traffic

This is the same pattern as in many other expressions:

• u gradu = in the city
• u školi = at school / in school
• u prometu = in traffic

Yes. Croatian word order is more flexible than English word order.

The original sentence is perfectly natural:

Kolona auta stoji na cesti zbog gužve u prometu.

But you could also say:

Zbog gužve u prometu kolona auta stoji na cesti.

This puts more emphasis on the reason first: Because of the traffic jam, the line of cars is stopped on the road.

Even though the word order can change, the cases help show the grammatical relationships.

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

So:

• kolona can mean a line or the line
• cesti can mean a road or the road, depending on context

Croatian relies on context, word order, and the situation to make the meaning clear.

It definitely can mean a traffic queue. In everyday Croatian, kolona is very commonly used for:

• a line of cars
• a queue of vehicles
• a convoy-like line

So in this sentence, kolona auta is a very normal expression for a line/queue of cars.

A few useful pronunciation points:

• c is pronounced like ts
  So cesti begins roughly like TSES-

• ž is like the sound in English measure
  So gužve has that zh sound

• j is like English y in yes
  So stoji sounds roughly like STOY-ee

Very rough English-style approximations:

• Kolona ≈ koh-LOH-na
• auta ≈ OW-ta
• stoji ≈ STOY-ee
• cesti ≈ TSES-tee
• gužve ≈ GOOZH-veh
• prometu ≈ PROH-meh-too

These are only approximations, but they are a good start.