Sentence:  Your hands rest on the bottom plane of the <WSD>box</WSD>, relaxed and open; forearms are parallel with the ground and elbows close to your body. Balls thrown from your right hand are aimed at the point to the left of center of the top of the <WSD>box</WSD>. When you hit this point the ball will land in your left hand. Balls thrown from your left hand are aimed at the point to the right of center of the top of the <WSD>box</WSD>. 
Meaning of the word marked with <WSD> tags:  A pattern usually performed with three balls where the movements of the balls make a boxlike shape.