Simplify the following text for a Grade 7 native English-speaking person.
Original: Metre per second ( U.S. spelling : meter per second ) is an SI derived unit of both speed ( scalar ) and velocity ( vector quantity which specifies both magnitude and a specific direction ) , defined by distance in metres divided by time in seconds .
Simplified: Metre per second is an SI unit of measurement of both speed and velocity . It is defined by the distance in metres divided by the time in seconds .