Speed is how fast something is moving. It's determined by the ratio of how far it will go in a period of time, divided by how long that period of time is (the duration). Speed is closely related to velocity. Just like velocity, speed is measured in distance divided by time, like meters per second, kph or mph.
The difference between speed and velocity is indication of direction. When we use the term speed, we are referring to how fast an object is moving. Velocity is the measured speed with direction.
Please see below to convert among various units for speed: