Advisors are the official voice of Funadvice, and are users just like you and me. Users get promoted to advisors when they've either been ranked highly by other users, or have just provided great answers.
If you read the upper left there, that's one description.
And if you read through past questions (try using "advisors" in the site search, in the upper right) and you get tons of info.
A trusted friend/helper. Someone who helps you out when you have a question. Someone who gives good advice.