Use the baseball bat to smack the ball into the cans. You have three balls to clear away the cans in each level. Look at the way the cans are stacked and pick the smartest targets.
The cans must be completely removed from the plank. Sometimes cans will fall over, but they might not fall onto the ground but land on the plank and come to a standstill there instead. Unlucky! In that case, you’ll have to hit them again to make them fall down.