2002 Dodge Intrepid Battery is dead

This is my mom's car and it hasn't been used in months. The battery was dead so I wanted to jump start it. When I lifted the hood, I felt like I was on another planet. There's a negative terminal that looks familiar, but I can't figure out where to attach the cable for the positive terminal. It's some kind of black cube that attaches to a metal post, using a red plastic clip. Any suggestions? Thank you for any help you can provide.