Motion
One of the first lessons in a physics class is motion: how an object moves, how fast it moves, where it moves, and at what rate it speeds up and slows down.
Physicists commonly use velocity and acceleration to characterize motion. Velocity refers to motion in a specific direction, while acceleration measures how fast or slowly velocity changes.
For example, when driving somewhere, both a driver and a car have velocity, meaning they move in a specific direction at some speed.
Said driver probably changes how fast they travel from time to time, alternately accelerating and decelerating.