En Dedans is a classical ballet term meaning “inward.” En dedans is always attached to another ballet term to describe the direction it should move.
For example, a pirouette en dedans would mean that a dancer is pushing their back leg to the front and turning “inward” to their supporting leg.
Another definition to think for en dedans is “from the back, to the front.” For example, a rond de jambe en dedans would start to the back and move in a circular motion to the side, then front.
En dedans is the opposite en dehors.