In order to study motion along a curved path, you must begin with understanding how to measure velocity along a curved path. Velocity vectors are used to measure velocity along a curved path.  A vector is more than a number. It is both magnitude and direction. On a graph or diagram, it is represented by an arrow.

Source: Angular Velocity Roll Coast, Rainer H. Michael, Wikimedia

Source: Vectors,  The Physics Classroom

Vectors require a special kind of addition because the result will vary depending on which way the vector is pointing. Follow this link to see more examples of vector addition.