What years old are you is that correct English?

No, that is not grammatically correct English. Here's why:

* "Years old" is used to describe age, but it's typically used after a number. For example, "I am 25 years old."

* "Are you" is the correct way to ask a question about someone's age, but it needs to be followed by the age.

Here are some correct ways to ask about someone's age:

* "How old are you?"

* "What is your age?"

* "How many years old are you?"