Setu means bridge; bandha means formation or construction. In this variation of Sarvangasana the body is arched backwards as if to form a bridge.
This asana is advanced, but by following easier methods one can gradually learn to achieve the advanced technique.
From Yoga A Gem for Women
This pose helps the functioning of the kidneys, regulates the menstrual periods, and checks the menstrual flow. It strengthens the back muscles, removes fatigue, rejuvenates the nerves, and improves the circulation around the chest. By the practice of this asana one develops self-confidence, will-power and steadiness of mind.
Technique from floor:
Lie flat on the floor.
Bend the knees, catch the ankles with the fingers and raise the chest, the thighs, and the abdomen.
Keep the back of the head and the shoulders on the floor. As the arms are extended in this movement, the chest expands easily.
Different Supported Variations using block and bolster:
Advanced Technique: from Sarvangasana the body is arched backwards to form bridge with bent knees or straight legs