What does "never mind" really mean?
I am trying to find out the answer for it. I have been hearing that for years, but I don't use it myself because I do NOT know the true meaning.
It means do not think about (something) and is used in a variety of contexts:
You may find even more uses in the Oxford Advanced Learner's Dictionary. Phrases of this sort are usually listed in good dictionaries, after the definitions of the headword.