The race is for the X team to skate hard and fast to the other side of the ice and shoot the puck at the END board (not the corner!) to end the round. If the O team hasn't gotten a shot off by the time X team has shot the puck at the end boards, X team gets a point.
Of course if O team gets the shot off before X team shots at the end board, they get point.
After 5 guys have gone, change.
A short video of how the drill is. You can't see the initial skater throwing it to the boards, racing around the pylon and finishing with his shot to the board.