An automobile, for example, travels so many kilometers in an hour.
Speed is a measure of how fast something is moving.
Speed is the rate at which a certain distance is covered and is always measured in terms of a unit of distance divided by a unit of time. The speed registered by the speedometer is actually the speed at that particular instant. Various distance and time units can be used for measuring speed. For long distances, kilometers per hour is commonly used. For shorter distances, meters per second is a more appropriate unit of measurement.