Alternator Cable Burned Off

[GA Cowboy]

Hey y’all, I recently noticed that my truck was having electrical issues. When I would drive down the road the radio would cut out, my lights would dim, and my blinkers wouldn’t blink. When I tested the battery I was only getting 12 volts with the truck running at idle, then when I looked at the alternator I noticed one of the cables was entirely burned off. I wish I knew more but I just wanted to ask how I should go about replacing this wire, and which wire it is. Thanks.