This posture is in Sanskrit called Utthita Hasta Padangusthasana and is one of the first balancing-on-one-leg postures. To enter the full posture, you’ll need some hamstring & hip flexibility, which the previous postures in the Ashtanga sequence gives you in time.
This tutorial also cues the correct vinyasa count in the posture, meaning it shows which movement is connected with an inhale or exhale.