WHAT IS ACCELERATION?

first  of all i shall  start from  speed, it the rate of change of the  distance, while  velocity is the rate of change of  displacement, velocity is vector quantity  it need  magnitude as well as direction to describe it.  while speed does not need to  direction  but magnitude, units of speed and  velocity is same.

Now  acceleration is the rate of change of velocity, it tells us that how velocity is changing  with respect to the  time.