Cool, and great question. Makes me think about how I can make it more clear.
The amount of steps the circles move is shown with that number.
So for example some levels move 7 right and 3 left which makes a huge difference in clear score depending on order and rotation direction.
A few levels have even number on both buttons, in those cases the player has to use a bomb to get rid of those marbles since they cannot be passed to the other side.