Which One Should I Choose?

When I launch Disk Utility, I'm asked to select a disk, volume, or image. I'm enclosing a photo of my hard drives. For instance, if I wanted to repair disk permissions on "Hard Disk," there appear to be two choices. Choice one: Hard Disk icon. Choice two: Hard Disk icon and number 74.5 GB ST380021A

Which one should I choose to repair?

The same choices are given to the other two hard drives that I have. Two choices per hard disk?

I use a Dual 1 GHz PowerPC G4 (QuickSilver 2002); running OS X 10.5.8 Leopard.