Back Foot
The term receiving with your back foot can seem a little confusing. If you are standing straight on to the player passing the ball you don’t have a back foot or a front foot. Maybe a good way to think about it to help you understand is if we talk a little about what you are trying to do when receiving the ball.
Let’s start first with the concept that when you receive the ball you most likely want to be facing the direction you want to go with the ball. This means that unless you are going straight forwards towards the player that kicked the ball to you (for the lack of a long explanation let’s just trust that most of the time you don’t want to go towards the player that passed the ball to you) then it makes sense to turn your body to the left or the right. This is called opening up (like a door opens on a hinge). If you use your front foot or foot closest to the passer then you are not over the ball with it in front of you. To keep the ball in front of you then you open up like a door let the ball pass your front foot then before it passes by you receive the ball with your back foot. You are now ready to go forward with the ball or any other direction you choose because the ball is in front of you and you are balanced and ready to make the correct decision for the moment.