Čim budemo imali vremena, kupićemo sladoled i sendviče blizu plaže.

Čim means as soon as or once.

It introduces a subordinate clause and shows that one action happens immediately after a certain moment or condition is reached:

• Čim budemo imali vremena... = As soon as we have time...

It is a very common word in Serbian for this kind of time relationship.

Budemo imali is the future II form of imati (to have).

It is built from:

• budemo = a form of biti
• imali = the past participle of imati

So:

• mi budemo imali = we will have / once we have

A useful detail: the participle agrees with the subject in number and gender. With a mixed group or a general we, Serbian normally uses imali. If the speakers were all female, it would be budemo imale.

Because after words like čim, kad, and often ako, Serbian usually uses future II for a future action in a subordinate clause.

The idea is:

• first: we get/find time
• then: we buy ice cream and sandwiches

So Serbian marks that first future event with future II:

• Čim budemo imali vremena, kupićemo...

Using imaćemo here would sound unnatural in standard Serbian.

Interestingly, English also avoids normal future in this kind of clause:

• As soon as we have time... not usually
• As soon as we will have time...

So the grammar is different in form, but the logic is somewhat similar.

Because Serbian normally says imati vremena for to have time.

Here vremena is in the genitive singular, and this is the standard idiomatic expression. It often has a partitive or indefinite sense: to have some time / enough time.

Very common examples:

• Nemam vremena. = I don’t have time.
• Imamo vremena. = We have time.

So even though the basic dictionary form is vreme, after imati in this meaning Serbian usually uses vremena.

Because this is a standard future I form built from kupiti + ćemo.

With many verbs in -ti, when the future auxiliary comes after the verb stem, Serbian writes it together:

• kupiti → kupićemo
• raditi → radićemo
• videti → videćemo

Another possible word order is:

• Ćemo kupiti sladoled...

But when the auxiliary comes after the verb stem, it is written as one word:

• kupićemo

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

Here the verb endings show we:

• budemo imali = we will have
• kupićemo = we will buy

So mi is unnecessary unless you want emphasis or contrast:

• Mi ćemo kupiti sladoled, a oni neće. = We will buy ice cream, but they won’t.

This is one reason Serbian can sound more compact than English.

Both words are direct objects, so they are in the accusative, but they look different because they differ in number.

• sladoled = accusative singular
• sendviče = accusative plural

More specifically:

• sladoled is masculine singular inanimate, and in that form the accusative looks the same as the nominative.
• sendviče is the plural accusative of sendvič.

So:

• kupićemo sladoled = we will buy ice cream / an ice cream
• kupićemo sendviče = we will buy sandwiches

If you wanted plural ice creams, you could say sladolede.

Because blizu requires the genitive case.

The noun plaža therefore changes to plaže:

• blizu plaže = near the beach

This is a very common pattern:

• blizu kuće = near the house
• blizu škole = near the school
• blizu grada = near the city

So the important thing to remember is: blizu + genitive.

Because Serbian has no articles.

So a noun like sladoled can mean:

• ice cream
• an ice cream
• the ice cream

depending on context.

Serbian expresses definiteness in other ways, such as:

• context
• word order
• demonstratives like taj, ovaj, onaj

So the sentence does not need separate words for a or the.

Yes. Serbian word order is fairly flexible.

This sentence begins with the čim clause because it sets up the timing first:

• Čim budemo imali vremena, kupićemo sladoled i sendviče blizu plaže.

But you could also say:

• Kupićemo sladoled i sendviče blizu plaže čim budemo imali vremena.

That keeps the same basic meaning. The original version simply puts more focus on as soon as we have time.