The fifth step of the one-handed backhand is the forward swing to contact. It’s a very simple step.
Once the racket is down and your hitting arm is completely straight, let go of the tennis racket with your non-hitting hand and swing your arm and the tennis racket around to your contact point, which is in front of your body. It’s very important that your arm and the racket swing from the shoulder as a unit. In other words, the relationship between you arm and the racket should not change.
Other than that, not much else going on. There’s a little bit of upper-body rotation back toward the net.
At about 40 seconds into the video we watch Andrej swing forward to his contact point. He lets go of the tennis racket with his non-hitting hand. His arm and the tennis racket then swing from the shoulder as a unit to his contact point, which is in front of his body. As he swings, he rotates his upper body back toward the net slightly but, other than that, not much else is happening during this step.