Here are the very basics. Fold equity is how often you think he will fold to a large bet or raise. If you add what you win in the pot all the times he folds...to what you plan to win whatever percentage of times that you win when he calls as opposed to what you lose when he calls and you lose...and you get the total EV of the play.
For example:
A very easy one.
$1/$2 blinds and both of you have $200
Villian raises to $8. You decide to flat call with
![The Ace of Hearts [Ah]](https://www.pofex.com/images/smilies/Ah.gif)
[Kh]
Pot is $16 and the flop comes
![The Seven of Hearts [7h]](https://www.pofex.com/images/smilies/7h.gif)
[4h][2d].
Villian bets $16. You decide to push all in. Im not saying I would do that. This is just an example.
He has a very tough decision. Lets say he has JJ. Lets say he folds 60% of the time.
60% of the time you win the pot right there.
The 40% of the time that he calls, you are the favorite with your 15 outs even though you have nothing right now.
So you win the med pot 60% of the time and of the other 40% of the time that he calls, you bust him more than half of those times.
You can do the math to determine what % of the time you need him to fold to make a play liek this +EV. In this case, if he has a pair lower than kings, its +EV even if he calls every time. But if he had KK, it would still be +EV if he only folded a small percentage of the time because you have 12 outs when he calls.