Could someone help me out with the terminology in that post?

"30/7ish villain opens in MP for 3-4BB. you defend your CO/button with XX (SC, PP, SA etc.)"

What's MP? Or BB? what does 3-4BB mean? CO/button? Also what's SA mean? I know SC is suited connectors and PP is pocket pairs but...

Thanks for the advice; gawd, I'm such a noob