As I understand fold equity, it is added equity in the pot depending on how often you can get the villain to fold from betting out/shoving.
So for example, say you have 10 8 offsuit on the button and you have 2BB and you shove all in. You are not going to have any fold equity there as its only another blind and a half for the SB and a blind for the BB to play. You are not going to get that pot without going to showdown.
Now lets say same situation but this time you have 12BB. This time you have fold equity. 12 BB would probably be a reasonable size of an SNG stack and if they called and lost, they could be in trouble. So they may very well fold hands that are better than your 10 8 like K7 or A4 not willing to risk that you have woken up with a *real* hand. In other words, 10 8 is typically not a profitable hand to shove with, but if you include the added equity you gain from people if they fold, it becomes a profitable move.
Hope this helps, and I hope that I am right in thinking that this is what fold equity is