It's the rating system that was introduced by the admin, to give a rating to a campaign, according to the performance maybe. Some bounties have more ratings while others are lesser, it might depend on different factors, I was unable to find that topic where it was discussed before, i think mods and admin can give ratings accordingly, but on what factors hard to tell right now. If you will visit the bounty section or signature section, you will see all of them have this rating setting on.

The photo you have shared is of a suggestion box section, where people share their opinions and suggestions, so I assume, better suggestions liked by the admin will have some ratings, the ones with no ratings might mean those were not good suggestions. Only the admin can shed more light on it now.