Hello Rajesh Gupta, welcome to our community!
To answer your opening question, the unity of velocity is meters per second (indicated in m/s). On some occasions, you could also see micrometers per second (μm/s) in case movement is really small.
However, the numbers you report seem a bit high for a Shake, so I would like to check its logs. Could you please download and post them here so that I can take a look? If needed, instructions on how to do so can be found on this page: Please read before posting!
Thank you!