Velocity

Just curious what does this mean on the display does it move the track a bit quicker?

velocity is how hard you hit the pad. in midi velocity is similar to the volume of the note 0-127 and can sometimes also be assigned to other things like pitch/filter/amplitude/etc. on the mpc when you do not have full levels turned on, the softer you hit the pad the lower volume it will be and that all gets stored in the sequencer.