If the object is in motion, the numerical expression for it's location will change. Reference Frames and Coordinate Systems. Any type of motion is always a relative change of position of an object relative to something else. Think of a Universe containing only a baseball and nothing elese. In such a Universe, the concept of motion of this baseball is meaningless, since there is nothing relative to which the ball can move.
Real baseballs move relative to their surroundings which in a baseball game is the baseball diamond.
In this example, the baseball diamond is the reference frame and the ball is the object in motion relative to the reference frame. To describe the motion of objects in general, the first step is to describe the reference frame relative to which the motion is to take place. Such reference frames are called coordinate systems. In practice, there are virtually an infinite number of ways to construct such coordinate systems, however. Think of Cartesian Coordinates as a way of locating things in a room such as the one you are sitting in.