They’re a nice quick reference for items that matter to some groups or to reflect the status of the repo at a given time. For example:
This is from one of my repos. The first is the latest version published to the package manager (in case I forget to update the docs). The second is the link to the docs. The third I believe I added before GitHub added the auto-detecting License tab in the repo header. And the fourth is a status of how “clean” the code is. None of them are terribly important really … but it is a nice quick-reference. It is a compact way to deliver a bunch of tidbits of information about the current status of the project.
I’m not sure if that clears anything up but I hope that helps!