Literally Hány = How // éves = years // vagyok = am I? Right?
But "Jól vagyok" means "I am fine", so then "I" and "am" are switched???
No, there is no actual "I" in that Hungarian expression. It is not needed, since the verb declination is enough to tell who the person is. I am is actualy én vagyok.
Seems like a question only someone so old that they've forgotten their age would ask.
It can also be a young child asking his mother. :)
Also though about that, but I think any kid old enough to ask that question would probably know their own age.
I do quite sometimes ask this question. In several cultures people don't care that much about their age. Some don't know their exact birthdays either.
Or...asked as a clarification question in response to someone asking you how old you are.
Or a riddle
My wife was born on the last day of the year. She asks me this all the time.