The handstand on forearms is commonly called the forearm stand.
There are also a number of other names like the lion or tiger stand. In yoga it has been called Pincha Mayurasana or the Feathered Peacock pose.
It is a great exercise for opening up the upper back and shoulders. It can also be used for lower back flexibility. In the following video you’ll see a woman doing just that. Pay attention to the different positions she takes with her legs, and also how she starts off with support in this position. If you’ve never done the forearm stand before I would highly recommend doing it against a wall the first time.
I typically teach the handstand on forearms as one of the lead-up stunts towards the true handstand, as once you’re use to it, it’s quite easy to balance in. For more details check out the Secrets of the Handstand Quick Start.