Kasirka zna koliko košta ovaj kaput.

Yes. Kasirka is the feminine form and means female cashier. The masculine form is kasir.

Serbian often shows gender directly in job titles and nouns for people. English usually does not, so in natural translation you may still just say the cashier unless the gender matters.

Because Serbian does not have articles.

So kasirka can mean a cashier or the cashier, depending on context. The same is true for many Serbian nouns.

In this sentence, ovaj kaput already means this coat, so it is specific even without an article.

Zna is the 3rd person singular present tense of znati, meaning to know.

It matches the subject kasirka, which is singular.

Present tense of znati:

• znam = I know
• znaš = you know
• zna = he/she/it knows
• znamo = we know
• znate = you know
• znaju = they know

Here koliko means how much.

It introduces an indirect question:

• koliko košta ovaj kaput = how much this coat costs

In other contexts, koliko can also mean how many, depending on what follows.

Examples:

• Koliko košta? = How much does it cost?
• Koliko knjiga imaš? = How many books do you have?

Košta is the 3rd person singular present tense of koštati, meaning to cost.

So:

• ovaj kaput košta = this coat costs

It is singular because the subject ovaj kaput is singular.

Compare:

• Ovaj kaput košta.
• Ovi kaputi koštaju.

Ovaj kaput is in the nominative singular.

Why? Because it is the subject of košta in the clause koliko košta ovaj kaput.

Also, ovaj agrees with kaput:

• masculine
• singular
• nominative

So:

• ovaj kaput = this coat

Yes, both are grammatical.

Koliko košta ovaj kaput is a very natural and common order. Serbian often places the verb early in this kind of clause.

Koliko ovaj kaput košta is also possible, but it may sound a bit more marked or give slightly more focus to ovaj kaput.

So:

• Kasirka zna koliko košta ovaj kaput. = very natural
• Kasirka zna koliko ovaj kaput košta. = also correct

Because this is an indirect question, introduced by koliko.

Serbian often uses da after verbs like znati when the following clause is a regular that-clause:

• Znam da je skup. = I know that it is expensive.

But when the clause begins with a question word such as koliko, gde, kada, zašto, ko, and so on, da is normally not used:

• Znam koliko košta.
• Znam gde živi.
• Znam kada dolazi.

Because the whole sentence is a statement, not a direct question.

The part koliko košta ovaj kaput is an indirect question inside the sentence, but the main clause is Kasirka zna... = The cashier knows...

Compare:

• Koliko košta ovaj kaput? = direct question
• Kasirka zna koliko košta ovaj kaput. = statement containing an indirect question

Yes. Serbian word order is fairly flexible.

You could hear:

• Kasirka zna koliko košta ovaj kaput.
• Kasirka zna koliko ovaj kaput košta.

Both mean the same basic thing. The difference is mainly one of emphasis and style, not grammar.

Usually koštati is about price or cost.

So this sentence is about how much money the coat costs.

If you want to talk about worth or value, Serbian often uses vredeti instead:

• Ovaj kaput vredi mnogo. = This coat is worth a lot.

So koliko košta is specifically the natural way to ask or say how much it costs.

Yes. Ovaj means this for a masculine singular noun in the nominative.

Since kaput is masculine singular, you get:

• ovaj kaput = this coat

The form changes depending on gender, number, and case. For example:

• ova knjiga = this book
• ovo dete = this child
• ovi kaputi = these coats

So ovaj is not one fixed form for every noun; it must agree with the noun.

It has two clauses:

1. Kasirka zna
2. koliko košta ovaj kaput

The second clause depends on the first one, so it is a subordinate clause. More specifically, it is an indirect question.

That is why the sentence has two verbs:

• zna
• košta