Earth is rotating ON an imaginary axis, not IN one.
Imagine a ball with a long pole stuck through the middle of it with the ends of the stick coming out of opposite sides of the ball. If you held the ends of the stick in your hands and made it go around with your fingers, the ball would turn at the same speed as the stick.
The stick is the "axis" - the line around which the ball is rotating, moving in a circle around that central line. The ball represents the Earth, rotating on its axis. There are no real sticks coming out of the Earth to show where the axis is located because the axis is imaginary, but the approximate locations where the "sticks" would be if they existed are the North and South Poles.