Nagrada i prijavnica su na stolu.

Because the subject is compound: nagrada i prijavnica = the prize and the application form.

In Croatian, when two nouns are joined by i (and), the verb is usually plural.
So:

• nagrada je na stolu = the prize is on the table
• prijavnica je na stolu = the application form is on the table
• nagrada i prijavnica su na stolu = the prize and the application form are on the table

So su is the 3rd person plural form of biti (to be).

Stolu is in the locative singular.

The preposition na can take different cases depending on meaning:

• na + accusative = movement onto something
• na + locative = location on something

Here the meaning is location: are on the table, not movement onto it.
So:

• na stol = onto the table
• na stolu = on the table

That is why you see stolu, not the basic dictionary form stol.

Here na means on or on top of.

So:

• na stolu = on the table

Croatian uses u for in/inside:

• u kutiji = in the box
• u sobi = in the room

A table is treated as a surface, so na stolu is the natural choice, not u stolu.

Both are feminine singular nouns.

A common clue is that many Croatian nouns ending in -a are feminine:

• nagrada = feminine
• prijavnica = feminine

That is why, if each noun were used alone, you would say:

• Nagrada je na stolu.
• Prijavnica je na stolu.

But together they take plural agreement: su.

Yes, you could.

Croatian word order is more flexible than English word order, because case endings and verb forms carry more grammatical information.

Both of these are natural:

• Nagrada i prijavnica su na stolu.
• Na stolu su nagrada i prijavnica.

The difference is mostly focus:

• Nagrada i prijavnica su na stolu focuses first on what is on the table.
• Na stolu su nagrada i prijavnica focuses first on where they are.

Normally, no. In a standard present-tense sentence like this, you keep the verb:

• Nagrada i prijavnica su na stolu.

Croatian does sometimes omit forms of biti in certain styles, headlines, notes, or very informal contexts, but for a normal full sentence, learners should use su here.

So this sentence should be learned with the verb included.

Croatian has no articles like English a/an/the.

So nagrada can mean:

• a prize
• the prize

and prijavnica can mean:

• an application form
• the application form

The exact meaning depends on context. Since you already know the meaning of the sentence, the Croatian itself does not need a separate word for the.

Prijavnica usually means an application form, registration form, or entry form, depending on context.

It comes from the idea of applying/registering/signing up.

So in different situations it could refer to:

• a school application form
• a competition entry form
• an event registration form

The core idea is a form you submit when you apply or register.

A simple learner-friendly pronunciation guide would be:

NAH-grah-dah ee pree-YAHV-nee-tsah soo nah STOH-loo

A few helpful sound notes:

• j is pronounced like English y
  • so prijavnica begins roughly pree-yav...
• c is pronounced ts
  • so prijavnica ends -tsa
• u is pronounced like oo
  • so su sounds like soo
• stress in Croatian is not always marked in writing, but for learners, this approximation is good enough to start with.

It is very close:

• Nagrada = prize
• i = and
• prijavnica = application form
• su = are
• na = on
• stolu = table in the locative, so on the table

So the structure is basically:

Prize and application form are on table

The main differences from English are:

1. Croatian has no article (the)
2. Croatian uses case endings, so stol changes to stolu
3. Croatian allows more flexible word order

Yes, that is grammatical, but it is less efficient and usually less natural unless you want emphasis.

Compare:

• Nagrada i prijavnica su na stolu.
  = normal, compact, natural

• Nagrada je na stolu i prijavnica je na stolu.
  = more repetitive, but possible

You might use the longer version if you want to emphasize each item separately, but in ordinary speech the combined version is better.

Not really in this sentence.

Animacy matters most in Croatian with certain masculine nouns, especially in the accusative. Here:

• nagrada and prijavnica are feminine
• stolu is locative after na
• the verb is simply plural because there are two subjects

So this sentence is a good basic example of:

• feminine nouns
• a plural subject
• na + locative for location

without any extra complications from animacy.