This special move allows Virgo to quickly dodge an opponent's attacks.
The image in this article illustrates the manner in which this move is performed; The black line represents Pegasus moving to where Virgo was, trying to hit it, and the yellow line represents the direction where Virgo goes in order to to easily dodge Pegasus.
This move is inspired by the actual ballet move, Entrechat, where the dancer does a quick jump and rapidly bumps her or his heels together.
Allegro is a quick pace. So, the bey "quickly" moves its "feet" like the dance move.