Definition of pot equity
Your equity pot is, if we make an analogy, your share of the theoretical cake. Let's take a simple example to illustrate. You are on the flop with AT on T-J-5. You are against a single opponent who has a specific range. You evaluate his range and compare it to your hand. Here, you give him a range of 19%. Against your hand, his range would be 43% pot equity and yours would be 57%. Theoretically, if the pot were 100, your pot equity would be 57 and his would be 43. Obviously, only one player will win 100% of the pot, so that's why we were talking about theoretical equity.
? What is the purpose of evaluating your pot equity?
Assessing your pot equity is a way of knowing where you stand in the hand. If, for example, we estimate our pot equity at 15% and our opponent flops a bet of 100 in 100, we know clearly that we can't call the bet. On the other hand, if we think we have 80% pot equity, it makes things easier. Also, if you identify a situation where your pot equity is 50% against your opponent, it's probably a good time to play your hand aggressively to maximize your chances of getting your opponent to fold while he has good equity in the hand.