Questions & Answers about Kaç yaşındasın?
A useful rough breakdown is:
- kaç = how many
- yaş = age / year of age
- yaşında = at the age of / years old
- -sın = you are for you singular, informal
So the whole sentence means How old are you?
Literally, it is closer to How many years old are you?
Because Turkish is an agglutinative language: it often builds meaning by attaching endings to a base word instead of using separate words.
Here, yaşında is the age expression, and -sın is the ending meaning you are. English uses separate words, but Turkish often joins them together, so yaşındasın is one word.
In Turkish, the idea of to be is often expressed with an ending rather than a separate verb.
So in Kaç yaşındasın?, the -sın at the end already means you are. That is why Turkish does not need a separate word like English are here.