3117 means e-lit, or e-literate. E-literate itself being a pun on illiterate. It's a derogatory reference to someone who thinks they are 1337 ("leet"), but not.
A hardo is a person who tries extremely hard at everything. Most times a hardo will try very hard at things that do not require excessive effort. For example, sports practices, gym class, etc.
Wow did you see Jack at practice today? What a hardo!