Position can become very critcal on the turn and the river. Lets say that you and 1 other opponent are in to see the flop. You are holding - A 10 suited diamonds, the flop is 2d 6d 8s. He was in the Small blind so he is first to act on the flop. He makes a bet into you. You re-raise his bet and he calls. Now on the turn he is likely to check to you. Lets say the turn is a 3 of clubs. You can either raise him to try to steal the pot right now if you think he isnt too strong or you now have the chance to take a free card. So you check and the river is a 9 of diamonds. since you checked on the turn he now bets out and you re raise with you nut flush, he goes all in with his set of 2's and you rake in a huge pot.
This is one way you can use position to your advantage