This is drill #6 in my book Simple Swims-Practices for balanced stable swimming.
Do this move once. Start in the Front Float with a glide (no leg movement), then bring right arm to the right leg, as you simultaneously push the right leg down toward the bottom of the pool. The left leg rises up slightly, as the belly turns slightly to the right. Keep the left arm forward and sloping down as you shift your weight to your left side. Balance on your left side in this shape as long as you can - it will be brief - without any extra leg movements. Use the action of the hand to leg to turn the belly/torso to face to the right. This is one cycle. Stand up, get a breath, then start again by going back into the Front Float.