Cubic bezier 1x1 yet code allows value greater than 1 for y value?

in one of the modules it specifically states that the function cubic bezier is only along a 1x1 grid so if this is so how come in the activity it says its ok to use a value greater than 1 i believe for one its y points.

A value that is greater than 1 on the y-axis is typically used to go farther than the final state of the animation and then return to to the final state at 1,1. This can often create a bouncing effect.