Here's a breakdown:

* Wave disturbance: A wave is a disturbance that propagates through a medium. This disturbance could be a vibration, a change in pressure, or an electromagnetic field.

* Medium: This is the material or space through which the wave travels. Examples include water, air, and even a vacuum (for light).

Essentially, the velocity of a wave tells you how quickly the disturbance is moving from one point to another.

Important Note: The velocity of a wave is distinct from the speed of individual particles within the medium. While particles in the medium might oscillate or move back and forth, the wave itself is a disturbance that travels through the medium.