Questions & Answers about Pljeskavice i ćevapi su na rešetki.
The singular forms are:
- pljeskavica → pljeskavice in the plural
- ćevap → ćevapi in the plural
So the sentence is talking about more than one grilled patty and more than one ćevap.
Su is the 3rd person plural form of the verb biti meaning to be.
Because the subject is plural — pljeskavice i ćevapi — Serbian uses the plural verb:
- je = is
- su = are
So Pljeskavice i ćevapi su... means The pljeskavices and ćevapi are...
They are in the nominative plural, because they are the subject of the sentence.
- pljeskavice = nominative plural
- ćevapi = nominative plural
In Serbian, the subject of a sentence is normally in the nominative case.