Inspecting your brake pads is to check the wear indicator grooves, most motorbike brake pads have a grooves molded or cut into the surface, so you can determine how much usable area of the parts is remaining.
The grooves will disappear when the brake pads is worn enough to the indication point to get the motorcycle parts replaced.
Once the pads is down to roughly about 2 millimeters then you need to change them....Drive Safe...