Plank Pose (Phalakasana in Sanskrit) is a strength building foundational posture.
It is often used when learning basic sun salutations, which are performed toward the beginning of a practice. The posture is a total body strengthener targeting the core, shoulders, wrists, and back.
Phalakasana translates to “plank” or “board”, because that is the position your body resembles while in the position. This is a fairly challenging asana (posture) strength-wise and may need to be modified by dropping the knees to the floor in the beginning when learning how to do it.