joint hinge 2D

Hello guys ,
can anyone please help me understand how Hinge joint 2D works?
I know that angle limits is to not let the object rotate more then the defined angles
like between 0 and 90
and what about motors how does it exactly work ?
I need to understand how it works so i can get the desired effects.
thanks for all

I believe you’ll find that explained in the following?

Please anyone can help?