We have main transmission line 11 KVA and our 25 kva Tranformer convert into 220 volt

If transmission line is 11 kva then why we use 25 kva transformer ?

Again, suspicious of a homework problem.

Besides, units are kVA not any other combination.

Volt is a proper name. Ampere is a proper name and k is x1000 and K = Kelvin.

Any guesses?

Overrating transformers is common -- to keep them from burning out prematurely in case of surges.

K is not Kelvin in this case. KVA is thousands of Volt-Amperes. It's a common rating found on electrical equipment like transformers.

A Volt-Ampere would be a Watt on a purely resistive system so KVA would be Kilowatts on a purely resistive system.