The speed of a wave is equal to the product of its wavelength and frequency. In other words, how fast a wave travels depends on how long it is (wavelength) and how many times it vibrates per second (frequency).
The distance between two consecutive points in a wave that are in phase with each other.
The number of complete cycles or vibrations of a wave that occur in one second.
The speed of an object in a given direction. In the context of waves, velocity refers to the speed at which the wave propagates through a medium.