Questions & Answers about Pivo je hladno.
Je is the 3rd person singular present form of the verb biti (to be).
So the structure is:
- pivo = the subject
- je = is
- hladno = the adjective describing the subject
In other words, Serbian is using the normal subject + to be + adjective pattern here.
Because adjectives in Serbian must agree with the noun they describe in gender, number, and case.
Pivo is a neuter singular noun, so the adjective must also be neuter singular:
- masculine: hladan
- feminine: hladna
- neuter: hladno
So:
- hladan čaj = cold tea
- hladna voda = cold water
- hladno pivo = cold beer
In Pivo je hladno, the adjective still agrees with pivo, so it stays hladno.
A very common clue is the ending -o or , which often marks a in Serbian.