When i was a child they said my mental age was 2 years behind. what does that mean?

You may have caught up to that perceived deficit. You may have posted an other similar message. It would be prudent to consult a neurologist to clear your doubts, as you seem to have normal mentation. Wish you good health!

Your post is a bit vague for a reasoned answer. At what age was this label applied to you? Mental functions include speech & language proficiency, self help skills, arithmetic skills, reading speed and information retention among others. There are ways to see if this is a continued problem or not. A simple answer is someone thought you were behind average kids in some skills at some age.