Nož i viljuška su za meso, a kašika je za supu.

The knife and fork are for meat, and the spoon is for soup.

Breakdown of Nož i viljuška su za meso, a kašika je za supu.

• biti: to be
• i: and
• a: and
• za: for

Questions & Answers about Nož i viljuška su za meso, a kašika je za supu.

Why is it su in the first part but je in the second?

Because the subject changes:

• Nož i viljuška = knife and fork → two things, so Serbian uses su (are)
• Kašika = spoon → one thing, so Serbian uses je (is)

So:

• Nož i viljuška su... = The knife and fork are...
• Kašika je... = The spoon is...

These are present-tense forms of biti (to be).

Why is a used here? Why not i or ali?

A often links two clauses by contrasting them lightly or setting them side by side.

So here:

• Nož i viljuška su za meso, a kašika je za supu.

means something like:

• Knife and fork are for meat, while a spoon is for soup.

Comparison:

• i = and (simple addition)
• ali = but (stronger contrast)
• a = and / while / whereas (mild contrast)

In this sentence, a is the most natural choice because the speaker is comparing two different utensils and their uses.

What does mean here?