Velocity is defined as the displacement per unit time. It is a vector quantity. The SI unit of Velocity and speed are same. In simple words velocity can be explained as speed in specific direction.
Mathematically,
Velocity = displacement / time .
Dimensional Formula of Displacement = M0L1T0
Dimensional Formula of Time = M0L0T1
Putting these values in above equation we get,
Dimensional Formula of Velocity = M0L1T-1
SI unit of Velocity is ms-1