The name, eight-limbed pose, comes from the eight points of contact between the body and the ground. It is also sometimes called knees-chest-chin pose.
Eight-limbed pose is often used as a preliminary pose to chaturanga dandasana, which requires more strength and control. This pose helps build the strength in the arms and core needed to perform chaturanga dandasana and may also be performed as an alternative in the first few rounds of sun salutations while the body is warming up.
As well as improving the flexibility in the spine and releasing tension in the upper back and shoulders, eight-limbed pose can also help strengthen the muscles of the back of the body. It is important when performing this pose not to collapse into the chest and only lower the chest fully if there is no discomfort or pain in the posture.