Ja volim kafu.

Because kafu is the accusative singular form of kafa.

In Ja volim kafu, coffee is the direct object of the verb volim (I like/love), so Serbian uses the accusative case.

• kafa = nominative singular
• kafu = accusative singular

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

• knjiga → knjigu
• voda → vodu
• kafa → kafu

So after a verb like voleti when the noun is the thing being liked, kafu is the expected form.

You can absolutely just say Volim kafu.

Serbian often omits subject pronouns because the verb ending already shows who the subject is.

• volim = I like/love
• voliš = you like/love
• voli = he/she/it likes/loves

So:

• Ja volim kafu. = I like coffee.
• Volim kafu. = also I like coffee.

Including ja usually adds emphasis, contrast, or extra clarity. For example:

• Ja volim kafu, a on voli čaj.
  I like coffee, but he likes tea.

Volim is the 1st person singular present tense form of the verb voleti.

The infinitive is:

• voleti = to love / to like

Present tense forms include:

• ja volim = I like
• ti voliš = you like
• on/ona/ono voli = he/she/it likes
• mi volimo = we like
• vi volite = you all / formal you like
• oni/one/ona vole = they like

So in this sentence, volim means I like or I love, depending on context.

It can mean either, depending on context.

With things such as coffee, music, movies, or food, voleti is often best translated as to like:

• Volim kafu. = I like coffee.

With people, it often means love:

• Volim te. = I love you.

So the Serbian verb is broader than English like and love, and the correct English translation depends on context.

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

So kafa or kafu can mean:

• coffee
• a coffee
• the coffee

The exact meaning depends on context.

For example:

• Volim kafu. = I like coffee.
• In another context, kafu could refer to a specific coffee, but usually the sentence is understood generally.

This is something English speakers often have to get used to in Serbian.

Yes. Serbian word order is fairly flexible.

The most neutral version is:

• Ja volim kafu.
• or simply Volim kafu.

But you may also hear:

• Kafu volim.
• Ja kafu volim.

These alternatives can sound more emphatic or put special focus on kafu or ja.

For example:

• Kafu volim, ali čaj ne volim.
  Coffee I like, but tea I do not.

So the sentence can move around more than in English, but the neutral beginner pattern is still subject + verb + object.

In Serbian, the verb ending tells you the person and number.

The ending -im here marks 1st person singular:

• volim = I like
• voliš = you like
• voli = he/she likes

That is why Serbian can often leave out the subject pronoun:

• Volim kafu. already clearly means I like coffee.

This is different from English, where the verb usually does not change much and the pronoun is almost always required.

It is singular.

The base form is:

• kafa = coffee, a coffee

In this sentence it changes to accusative singular:

• kafu

A plural form would be different. For example, nominative plural is:

• kafe = coffees

So kafu here means one general coffee as a mass noun or singular noun form, not plural.

Yes, it is completely normal and natural.

• Volim kafu. = I like coffee.

This is how you would normally express a general preference for coffee.

If you say Ja volim kafu, that is also correct, but with ja it may sound a bit more emphasized unless the context calls for it.

You add ne before the verb:

• Ne volim kafu. = I do not like coffee.

If you keep the pronoun, you get:

• Ja ne volim kafu.

This is the standard way to negate present-tense verbs in Serbian.

A simple learner-friendly pronunciation is:

• ya VO-leem KAH-foo

A few helpful notes:

• j in Serbian sounds like English y in yes
• v is like English v
• lj is a special Serbian sound, but it does not appear here
• u is like oo in food

So:

• Ja sounds like ya
• volim sounds roughly like VO-leem
• kafu sounds roughly like KAH-foo

Stress in Serbian can be tricky, so this kind of approximation is useful at first.

You could, but it is not the same kind of sentence and is less natural for a general statement like this.

• Volim kafu = I like coffee / I love coffee
• Sviđa mi se kafa literally works more like Coffee is pleasing to me

Sviđati se is often used for reacting to something specific:

• Sviđa mi se ova kafa. = I like this coffee.
• Sviđa mi se ova pesma. = I like this song.

For a general preference such as I like coffee, Volim kafu is the most natural choice.

If coffee were the subject, it would stay in the nominative:

• Kafa je vruća. = The coffee is hot.
• Kafa je dobra. = Coffee is good.

Here kafa is the subject, so it uses the basic dictionary form.

But in Ja volim kafu, it is the object, so it becomes kafu in the accusative.

This contrast is very important in Serbian:

• kafa = subject form
• kafu = direct-object form

Yes. Voleti is a very useful early verb because it appears in many everyday sentences.

You can use it with:

• people: Volim svoju porodicu.
• food and drink: Volim kafu.
• activities: Volim da čitam. = I like to read.
• places and things: Volim Beograd., Volim muziku.

It is a high-frequency verb, and it also helps you practice:

• present-tense conjugation
• object case forms
• optional subject pronouns

So Ja volim kafu is a very good beginner sentence to study.