>what are Reputation Points?
A frivolous and pointless feature that nobody cares about.
>And how exactly does this system work?
If you see a post you like, you can give the poster good rep. This increases that person's reputation by a certain number of points depending on how many points you have. The more points you have, the more green bars you have under your name, and people can (theoretically) judge how good of a member you are. Likewise, the opposite is true with bad rep and red bars.