I don't know what this wire is or where it attaches on my 1997 jimmy

[Emery Prefontaine]

The first pic is me holding it and the second pic is where it attaches to the frame. It's right beside the battery tray. And I just don't know if it attaches it to the negative or positive post clamps on the battery or somewhere else. https://docs.google.com/document/d/1IhxxVGZizxvL2DnDBdrXJ_xbQic3wL7woS5Hzs73csQ/edit?usp=sharing