What do you mean by Offsets?

I looked around the internet but couldnt find the proper meaning of offsets and how to use them. I downloaded a model of the sawyer arm and tried adding the inverse kinematics script from the assetstore. The sample scene had an arm with offsets but when i changed the offsets to zero , the sample arm acted weird. i just wanna know how to add these offsets to my model so that they work properly.

Thanks,