High elbow recovery is a freestyle phase in which the arm is bent above the water to achieve recovery and to ensure proper hand entry.
Bending your arm in the recovery phase reduces stress on your shoulder joint and saves more energy than when extending your arm.
The elbow should create about a 90 degrees angle before your hand goes in the water at a 45 degrees angle. And that goes with rolling your shoulders (as if you are trying to reach something with the arm in front while moving your other shoulder to the side as you prepare to lift your elbow). Rolling your shoulders helps you glide better and prevents shoulder joint injury.