what is it?

That achievement is no more achievable.
There used to be a group called Unibash, which used to make people go through optional tests to see their knowledge on certain subjects (Ingame, Market, Clans). After the test was taken, we (Unibash), would judge if the taker passed or failed. If they passed, they would get an achievement coresponding to the test taken. Unibash has since been dismantled, therefore the achievements are unable to be achieved

As duck said, it's no longer achievable.
Old Unibash

Besides that, your question has been answered; closing.