Really simple ! Just use the blue-colored "stick" to prevent the ball (red) from striking the right side wall.
The stick only moves vertically and can be controlled by the up/down arrow keys of your keyboard.
As the name suggests, the ball bounces off the walls and any obstacles in the rink without losing speed.
The challenge is to use your judgement and anticipation (your physics sense) to judge where the ball is likely to hit the wall and bring your stick to that position to ward off collision between the wall and the ball.
PS: This is my first C2 game and was designed primarily for FB. You need to be logged into FB to play higher levels (you can still play level 1 without logging into FB).