From my understanding, status points is different between each community. For example, I used status points and the level system to understand who in the community are new vs. experts with Jive functionality. It was helpful when I was developing use-cases, making UI changes, etc. because I could reach out to my "experts" and get constructive feedback. You can also use to incentivize too--if you have a rewards or value program.
Jive info on status points and levels can be found in the Jive documentation (Click on Jive Help from the User Menu).
Points and levels can be customized in the admin console under People / Settings / Status Level Settings. Have fun!
Points are a nice feature to see who's really active. They work without any maintenance.
With an additional gamification module one can also create missions, award badges and so on. This community is a good example with many badges.