There are many variations on the basic right angle sex position. In this variation our model B has both legs up, not bent at the knee, and they are leaning against their partner A. Changing your leg positions can change how this sex position feels, and stretching out can be great if you are used to tensing up during arousal or climax.
Also, notice how A's hands are on B's hips, which allows A to move B around, offers support and some traction, and also nice physical contact. At the same time one of B's hands is grabbing A's arm, and the other is resting. One of the great things about the right angle sex position is the amount of variation it allows in both partners use of their legs and arms, the angle of penetration, and the amount of physical contact.