Stand upright facing away from the machine with your feet shoulder-width apart and gripping the handle with an overhand grip in front of your hip at shoulder-width while your other hand is rested behind your back.
Exhale and raise your arm while keeping it straight.
Continue raising your arm until it becomes parallel with the ground.
Inhale and lower your arm, keeping it straight and returning to the starting position.
After all reps are completed, switch sides and repeat the movement. 10 reps prescribed means you should perform 10 reps on each side (20 total).