What is this wire?
#12
One end should connect to the hood. We think of ground strap as the battery ground. This is a body ground. It is a corrosion prevention measure. Dissimilar metals in the present of moisture can set up a galvanic cell, basically a low voltage battery. As electrons pass from one metal the other it takes metal with it. This is how plating occurs. The ground keeps the parts at the same electric potential and helps prevent corrosion. It's the same thing you see in plumbing when you have a steel hangaer on a copper pipe, you will notice the green copper building up on the steel.