Kupujem četiri jabuke.

Kupujem is the 1st person singular present tense form of the imperfective verb kupovati, meaning to buy in an ongoing or habitual sense.

So:

• ja kupujem = I buy / I am buying

It tells you:

• person: 1st person = I
• number: singular
• tense: present

This is why Serbian does not need a separate word for I here.

Serbian often leaves out subject pronouns when they are already clear from the verb ending.

In kupujem, the ending -em already shows that the subject is I.

So both of these are possible:

• Kupujem četiri jabuke.
• Ja kupujem četiri jabuke.

The version without ja is very normal and natural. Adding ja usually gives extra emphasis, like:

• I am buying four apples

It can mean either one, depending on context.

Serbian does not have a separate progressive form like English I am buying. The present tense of an imperfective verb often covers both:

• I buy
• I am buying

So Kupujem četiri jabuke could mean:

• I am buying four apples right now
• I buy four apples, depending on the situation

Context tells you which meaning is intended.

This is about aspect, which is very important in Serbian.

• kupovati → imperfective → kupujem
• kupiti → perfective → kupim

Kupujem focuses on the action as ongoing, repeated, or in progress.

Kupim comes from the perfective verb and usually refers to a completed act. In Serbian, perfective present often has a future-like meaning in many contexts.

So:

• Kupujem četiri jabuke. = I am buying / I buy four apples
• Kupiću četiri jabuke. = I will buy four apples

For a simple present statement like this, kupujem is the natural choice.

Četiri is the standard form of four used with nouns in sentences like this.

Serbian numbers change in some situations, but here četiri is exactly the form you need before jabuke.

Compare:

• jedna jabuka = one apple
• dve jabuke = two apples
• tri jabuke = three apples
• četiri jabuke = four apples
• pet jabuka = five apples

The biggest thing for learners is not usually the form četiri itself, but the noun form that comes after it.

Because Serbian uses a special counting pattern after 2, 3, and 4.

With četiri, the noun does not take the same form as it does after 5 or more.

So:

• četiri jabuke = four apples
• pet jabuka = five apples

This is one of the most important number patterns to learn in Serbian:

• 1 → singular: jabuka
• 2, 3, 4 → jabuke
• 5 and more → jabuka

So četiri jabuke is correct, while četiri jabuka is not.

As a whole, četiri jabuke is the direct object of kupujem, so it functions as the object of the verb.

However, after numbers like dve, tri, četiri, Serbian uses a special counted-noun form. For jabuka, that form is jabuke.

This can be confusing because jabuke looks like more than one grammatical form:

• nominative plural
• genitive singular
• the form used after 2, 3, 4

So the safest learner-friendly explanation is:

• četiri jabuke is the correct counting form after četiri
• the whole phrase is the object of kupujem

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

The neutral, natural order here is:

• Kupujem četiri jabuke.

But other orders are possible for emphasis:

• Ja kupujem četiri jabuke. = emphasizes I
• Četiri jabuke kupujem. = emphasizes four apples

Even though word order can move, the basic meaning stays the same because the grammar endings help show the relationships between words.

This is very useful to compare:

• Kupujem jednu jabuku. = I am buying one apple
• Kupujem dve jabuke. = I am buying two apples
• Kupujem tri jabuke. = I am buying three apples
• Kupujem četiri jabuke. = I am buying four apples
• Kupujem pet jabuka. = I am buying five apples

So the important pattern is:

• 1 → jabuku in this sentence
• 2–4 → jabuke
• 5+ → jabuka

This is why number phrases are such a big grammar topic in Serbian.

A simple approximate pronunciation for an English speaker is:

• Kupujem ≈ KOO-poo-yem
• četiri ≈ CHEH-tee-ree
• jabuke ≈ YAH-boo-keh

A few helpful notes:

• j in Serbian sounds like English y
• č sounds like ch in chocolate, but a bit firmer
• every vowel is pronounced clearly: a, e, i, o, u

So the full sentence is roughly:

• KOO-poo-yem CHEH-tee-ree YAH-boo-keh

The dictionary form is jabuka, meaning apple.

So:

• jabuka = apple
• jabuke = a form used for apples, including after 2, 3, 4

When learning vocabulary, you would usually memorize the noun as:

• jabuka = apple

Then later you learn its other forms, such as:

• jabuke
• jabuka
• jabuku

because Serbian nouns change form depending on grammar.