The change in position or displacement (x) divided by the time intervals (t) during which the displacement happens is the definition of average velocity.
Based on the direction of the displacement, the average velocity might either be positive or negative. Meters per second (m/s or ms-1) is the SI measure for average velocity.
The displacement of a body, or the shortest distance it must go during a trip, is calculated as the displacement multiplied by the time interval over which it covered that distance.