Potrošač duguje kamatu.

Because it is the direct object of the verb duguje.

The basic dictionary form is kamata. In this sentence, it changes to the accusative singular:

• kamata = nominative singular
• kamatu = accusative singular

So:

• Potrošač = the subject
• duguje = owes
• kamatu = the thing being owed

This is very common with feminine nouns ending in -a:

• kuća → kuću
• žena → ženu
• kamata → kamatu

Duguje is the 3rd person singular present tense form of the verb dugovati, which means to owe.

So the pattern is:

• ja dugujem = I owe
• ti duguješ = you owe
• on/ona/ono duguje = he/she/it owes

Since potrošač is singular, the verb is also singular: duguje.

Because Serbian does not use articles like English does.

English requires things like:

• the consumer
• a consumer

Serbian usually just says:

• potrošač

The exact meaning depends on context. So Potrošač duguje kamatu could mean:

• The consumer owes interest
• A consumer owes interest

Context tells you which is more natural.

Yes, potrošač is grammatically masculine singular.

It ends in a consonant, which is very typical for masculine nouns in Serbian. In this sentence it is in the nominative singular, because it is the subject.

If you wanted to refer specifically to a female consumer, you would often use potrošačica.

So:

• potrošač = male consumer / consumer in a general masculine form
• potrošačica = female consumer

It can cover both ideas, depending on context.

The Serbian present tense often corresponds to English:

• simple present: owes
• present progressive: is owing

So Potrošač duguje kamatu usually just means that the consumer has an obligation to pay interest. English normally says owes here, not is owing, but grammatically Serbian is simply using the present tense.

Yes. Serbian word order is more flexible than English because case endings show grammatical roles.

The neutral order here is:

• Potrošač duguje kamatu.

But you could also hear:

• Kamatu duguje potrošač.
• Potrošač kamatu duguje.

These alternatives change the focus or emphasis, not the core meaning. Because kamatu is accusative and potrošač is nominative, Serbian speakers can still tell who owes what.

Mainly from the case forms.

• potrošač is in the nominative, which is the normal case for the subject
• kamatu is in the accusative, which is the normal case for a direct object

So even if the order changed, the cases would still show the roles.

This is one of the big differences from English: Serbian relies much more on endings than on strict word order.

The dictionary forms are:

• potrošač = consumer
• dugovati = to owe
• kamata = interest

In the sentence, potrošač happens to stay in its dictionary form, duguje is a conjugated verb form, and kamatu is the accusative form of kamata.

No. Kamata means interest, not the debt itself.

A related noun is dug, which means debt.

So there is an important difference:

• dug = debt
• kamata = interest

That means Potrošač duguje kamatu specifically says the consumer owes interest, not necessarily the whole debt amount.

A rough pronunciation is po-tro-shach.

A few useful points:

• č sounds like ch in church
• š sounds like sh in shoe
• Serbian spelling is quite phonetic, so words are usually pronounced close to how they are written

So:

• potrošač ≈ po-tro-shach
• duguje ≈ doo-goo-yeh
• kamatu ≈ ka-ma-too

These are only approximate English-based guides, but they are close enough for a learner to start with.

Not in the same straightforward way.

The most natural sentence here is Potrošač duguje kamatu.

There is also an expression with dužan, but it works differently and often needs a fuller structure, for example:

• Potrošač je dužan da plati kamatu. = The consumer is obliged to pay interest.

So:

• dugovati = to owe
• biti dužan = to be obliged / to owe, depending on structure and context

For this simple sentence, duguje is the most direct and natural choice.