I'll explain them as best I can linking them together:
Motion - Describes general movement of an object, has no unit, an object is either in motion or it is not.
Speed - A scalar quantity, that is to say it can only be positive and has no direction to it. This is measured in m/s.
Acceleration - The differential of a speed time graph, it is the rate of change of speed (i.e. how much speed changes per unit time), and is measured in m/s/s (m/s^2)
Velocity - The Vector version of speed, that is to say it has a direction and can be negative. The velocity of an object also tells us the direction it is travelling, rather than merely how fast it is travelling.
