How can I be the best executive istant?

I'm finishing up school, and I have taken a job being an executive istant to the CEO of a forune 500 company. It's high stress, and very technical as it is a telecommunications company. I don't fully understand all the lingo yet, and my bost (who i'm supposed to be helping) is too busy to teach me what to do on a daily basis. I can do everything that he's asked me to do, but there's got to be more than just waiting, right? What should I be doing to help him during the time frames when I don't have anything else to do? Please help! I want to be able to do this well!!