This is a resistance exercise that targets the biceps, the muscles located at the front of your upper arms. It is typically performed using a cable machine found in most gyms. It's an effective exercise to strengthen and tone the biceps while offering the benefit of constant tension on the muscle throughout the entire range of motion.
First, place both cable pulleys as low as possible, then grab the handles in each hand and position yourself in the middle of the pulleys. Also make sure you are far enough away that there is no bend in your arms and they are pointing at the pulleys and your palms facing up.
This is the starting position.
From here curl one of your hands towards you, by bending at the elbow until the arm is fully flexed or as far as you can. After this, slowly return the arm back to the starting position. Repeat on the other arm. Once you have done both this is one repetition, now repeat this for the desired amount.
If you have limited gripping ability try using the Active Hands Gripping aids or D-Ring Aids clipped straight into the carabiner to make this exercise as safe as possible.