Na stolu su dva jaja.

Serbian word order is much more flexible than English word order. Starting with Na stolu puts the location first: On the table, there are two eggs.

A more neutral version would be Dva jaja su na stolu, but Na stolu su dva jaja is very natural when you are first pointing out what is in a certain place.

Because na changes case depending on whether you mean location or movement.

• na stolu = on the table, with locative, because the eggs are already there
• na sto = onto the table, with accusative, because something moves there

So in this sentence, stolu is the locative singular of sto (table).

Su is the 3rd person plural present of biti (to be). Here it simply means are.

So:

• su = are

The sentence literally looks like On the table are two eggs.

Because Serbian does not need a dummy subject like English there.

English says:

• There are two eggs on the table.

Serbian simply says:

• Na stolu su dva jaja.
• literally: On the table are two eggs.

So nothing is “missing” in Serbian; it is just a different sentence structure.

Both mean two, but they change according to gender.

• dva is used with masculine and neuter nouns
• dve is used with feminine nouns

Jaje (egg) is a neuter noun, so you say dva jaja.

Because jaje is singular: egg.

To say two eggs, you need a plural/count form, and here that form is jaja.

So:

• jaje = egg
• jaja = eggs

You may also come across dva jajeta in some usage, but dva jaja is very common and natural.

In this sentence, dva jaja functions as the subject of the sentence.

With numbers like dva, Serbian uses a special counting pattern that learners are best off treating as a set expression at first: dva + noun. So for practical purposes, just learn:

• dva jaja = two eggs

and recognize that the whole phrase is the subject of su.

Yes. That is also correct.

The difference is mainly one of focus or emphasis:

• Na stolu su dva jaja = focuses first on where
• Dva jaja su na stolu = focuses first on what

The basic meaning stays the same.

Normally, no.

Serbian often leaves out subject pronouns because the verb form already shows the person, but it does not normally leave out the verb to be in a sentence like this.

So:

• Na stolu su dva jaja. = correct
• Na stolu dva jaja. = incomplete in normal speech, though it might appear as a note or caption

Because Serbian has no articles.

English must choose between a table / the table and eggs / the eggs, but Serbian usually leaves that to context.

So Na stolu su dva jaja most naturally means:

• There are two eggs on the table

Context would tell you whether the table or eggs are already known.