On his forum, I see on accounts, medals and projects. What is a medal?
The amount of medals you have gets you higher in the social rankings.
People give you medals for courtesy.
Here, have a medal 
No idea, I’ve only been here for about 5 months, 
To give a medal, press the ‘Appreciate’ button to the right of anyone’s post.
How social ranks are evaluated is described here. Medals are to show appreciation for good work, a well written post, helpful advice, etc.
Those are silly statistics that Riven came up with, if you’re referring to your rank (JGO Wizard, Senior Member, Senior Noob, etc.) that is calculated based on (I think) the number of posts you’ve made, the number of medals you have, and the number of projects you have. Maybe some other things as well, I can’t recall.