Svaka stavka ima kategoriju.

Because stavka is a feminine singular noun.

In Serbian, words like svaki (each / every) must agree with the noun they describe in:

• gender
• number
• case

So you get:

• svaki for masculine singular
• svaka for feminine singular
• svako for neuter singular

Since stavka is feminine, the correct form is svaka stavka.

Stavka is in the nominative singular.

It is the subject of the sentence — the thing that has something.

So in Svaka stavka ima kategoriju:

• svaka stavka = the subject
• ima = the verb
• kategoriju = the direct object

The basic pattern is:

subject + verb + object

Because kategoriju is in the accusative singular.

The verb imati (to have) takes a direct object, and direct objects are usually in the accusative case.

The noun changes like this:

• kategorija = nominative singular
• kategoriju = accusative singular

Since the sentence says that each item has a category, category is the object, so Serbian uses kategoriju.

Yes. Ima is the 3rd person singular present tense of imati (to have).

Here are a few present-tense forms:

• imam = I have
• imaš = you have
• ima = he/she/it has

Because the subject is svaka stavka (each item), Serbian uses singular ima, not plural.

Because svaka stavka is grammatically singular.

Even though every item refers to many items in general, Serbian treats each/every + singular noun as singular:

• Svaka stavka ima... = Each item has...
• not Svaka stavka imaju...

This works the same way as in English:

• Every item has
• not Every item have

Serbian normally does not use articles.

So:

• stavka can mean an item, the item, or just item
• kategoriju can mean a category or the category

The exact meaning depends on context.

That is why the sentence has no separate words for a or the.

No, Serbian word order is fairly flexible, because case endings show the grammatical roles.

The neutral, most straightforward order is:

Svaka stavka ima kategoriju.

But other orders are possible for emphasis, for example:

• Kategoriju ima svaka stavka.
  = Emphasizes category

• Svaka stavka kategoriju ima.
  = Possible, but more marked or stylistic

So the original sentence is the most natural neutral version.

Stavka is a feminine noun ending in -a.

Many Serbian feminine nouns end in -a, and they often follow similar case patterns. For example:

• nominative: stavka
• accusative: stavku
• genitive: stavke

In this sentence, though, stavka stays in the nominative because it is the subject.

Yes.

Both nouns end in -a and are feminine:

• stavka = feminine
• kategorija = feminine

That matters because:

• svaka must match stavka
• kategorija changes to kategoriju in the accusative

So this sentence is a good example of:

• agreement with the subject
• case change in the object

Yes, in many contexts svaka can correspond to both each and every.

So Svaka stavka ima kategoriju can match:

• Each item has a category
• Every item has a category

The difference is usually more about natural English style than about a major grammar difference in Serbian.

A rough pronunciation for an English speaker would be:

SVA-ka STAV-ka EE-ma ka-te-GO-ri-yu

A few helpful notes:

• sv in svaka is pronounced together
• j in Serbian sounds like English y
• so kategoriju ends roughly like -ree-yu

A more broken-down version:

• Svaka = SVA-ka
• stavka = STAV-ka
• ima = EE-ma
• kategoriju = ka-te-GO-ri-yu

No. Kategoriju is singular accusative.

If it were plural, the form would be different. The sentence as written clearly says that each item has a category / one category in a general grammatical sense.

So:

• kategoriju = singular object
• not a plural form

This does not always strongly emphasize exactly one in all real-world contexts, but grammatically the noun is singular.