Definition of pot control
When you make pot control, it is because you make sure to keep the pot size small. There are several tricks to make a pot control. Usually a player will roll a pot control with a medium hand or a draw. See below for a concrete example.
An example of a pot control
You spike A2 on the button and the small and big blind call you. The flop falls 6-7-J with 2 spades. Here, in the range of blinds, there are a lot of brelans, 2 pairs, fifths prints, etc. After the blinds check the flop, you could bet to make them fold, but you dread the check-raise. If one of the players you check-raise, it will swell the pot which could be very big and if you don't hit the turn, you will be forced to fold your hand. You also don't want to push all in the flop with a single draw. For all these reasons, you go from a check-back in position with your draw (to make a pot control). Thereafter, if a player decides to bet on turn, the pot won't be out of proportion.