It says that Charisma increases non-player character disposition, I've never understood what that meant?

http://en.wikipedia.org/wiki/Disposition

Loosely translated it means that ur companions in FNV (Boone, ED-E etc.) will be braver, tougher and do more damage.

I thought it's just a leftover from Oblivion, where NPCs had an actual disposition meter that affected their inclination to speak to you and trade with you.