Sir Issac Newton discovered the principle that for every
action there is an equal and opposite reaction. This
is called his Third Law. The water pours out of the small
hole and its force pushes the carton in the opposite
direction. This is what makes it turn. The more holes
there are, the faster the carton turns.
This is similar to some turbines. Some turbines use
water or steam that is forced a high speed through many
small holes to turn a turbine around. The turbine is
connected by a shaft to an electrical generator, which
makes electricity when it is turned.