The term fold equity refers to the % chance that by pushing all in or raising that your opponent will fold, thus equalising the odds of the hand if it had to go to showdown.
I.E. against a random hand, 23o is 32.2%, but given the odds that if you raise allin vs the big blind and he is a tight player and would only call with QQ+, your hand recieves "fold equity" and thus it becomes a profitable play.
As for general advice on SNGs, a good thread to start on is here:
FAQ
And another good way to find good posts are to familiarize yourself with the search function so that you can find topics related to any specific questions you might have.