Za salatu ću narezati krastavac i paprike.

Because za here means for in the sense of intended for / for the purpose of. After za, Croatian normally uses the accusative case in this meaning.

• dictionary form: salata
• accusative singular: salatu

So:

• za salatu = for a salad / for the salad

This is a very common pattern in Croatian:

• za juhu = for soup
• za ručak = for lunch
• za tortu = for the cake / for making a cake

This is how the Croatian future tense is often built.

The future here is made from:

• the auxiliary ću = I will
• the infinitive narezati = to slice / to cut up

So literally it is something like:

• ću narezati = will cut up

Croatian has special word-order rules for short words like ću. It often appears in the second position of the sentence or clause. That is why you get:

• Za salatu ću narezati ...

You can also say:

• Narezat ću krastavac i paprike.

In that version, the infinitive usually loses its final -i before ću:

• narezati → narezat ću

Both are normal.

Narezati is a perfective verb. It suggests cutting something up as a completed action, often into slices or pieces.

• rezati = to cut, to be cutting, to cut in general
• narezati = to cut up, slice up, finish cutting

In this sentence, the speaker is talking about one completed future action, so narezati is very natural.

This is one of the big differences from English: Croatian often chooses between two verb aspects:

• imperfective for ongoing, repeated, or general action
• perfective for a completed whole action

They are the direct objects of the verb, so they are in the accusative case.

However, their forms may look familiar because Croatian accusative does not always look different from the dictionary form.

krastavac

This is a masculine inanimate noun. For masculine inanimate nouns, the accusative singular is usually the same as the nominative singular.

• nominative: krastavac
• accusative: krastavac

paprike

This is the accusative plural of paprika.

• nominative singular: paprika
• nominative plural: paprike
• accusative plural: paprike

So both objects are accusative, even though the forms do not look very dramatic.

It simply means the speaker plans to cut up:

• one cucumber
• more than one pepper

Croatian often leaves number exactly as intended. So this sentence suggests one cucumber and several peppers.

If the speaker meant more than one cucumber too, they could say:

• krastavce i paprike

So this is not a strange grammar rule—just the quantity the speaker has in mind.

It can mean both, depending on context.

• paprika = pepper / bell pepper
• paprika = paprika powder / the spice

In this sentence, because the speaker is going to slice it for a salad, it clearly means the vegetable, not the spice.

This is very common in Croatian: context tells you which meaning is intended.

Yes. Croatian word order is fairly flexible, though not completely free.

This sentence starts with Za salatu to foreground the purpose:

• As for the salad / For the salad, I'll cut up...

Other natural versions include:

• Narezat ću krastavac i paprike za salatu.
• Krastavac i paprike ću narezati za salatu.

The meaning stays very similar, but the emphasis changes.

One important thing remains: short forms like ću usually follow the second-position rule, so they tend to come early in the clause.

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

So krastavac can mean:

• a cucumber
• the cucumber

And paprike can mean:

• peppers
• the peppers

Context tells you which one is meant. This is normal in Croatian and one of the first things English speakers have to get used to.

Sometimes, but it would not mean exactly the same thing.

• za salatu = for the salad, meaning for the purpose of making/preparing a salad
• u salatu = into the salad, focusing more on something going into it

In this sentence, za salatu sounds very natural because the speaker is talking about preparing ingredients for a salad.

So:

• Za salatu ću narezati ... = I’ll cut these up for the salad.
• ... u salatu would shift the focus more toward them ending up inside the salad.

Yes, it is natural and normal.

It sounds like something someone would say while cooking:

• Za salatu ću narezati krastavac i paprike.

A very common alternative in speech would be:

• Narezat ću krastavac i paprike za salatu.

Both are idiomatic. The original version just gives a bit more emphasis to za salatu at the beginning.