I think the reputation points are part of the vbulletin software. On another site I frequent you have to check out your User CP to see your points and why you received them. As Dusty said that green box is your reputation in a visible format to all who read your posts. As your number of points grow you will have more green boxes. Placing your cursor on the green boxes will reveal the reputation. That reputation will change as you receive more points. Later when members have more rep points the points they give you will be greater than someone with only a few. On the other site I have over 20,000 and I can affect a reputation quickly. I do not give negative because I can really drop someone's rep. Here I have a whopping 20.