The add-on solves the problem of having a badge/counter in your navigation bar.
XenForo 2.x has navigation manager, where you can create any tabs/sub-menu, however, it does allow to put some additional badge on them (for example, when you need to highlight one of your tabs with a "New!" badge, or want some type of counter on the tab). This add-on can also be used by other add-ons that need to add a dynamically generated content
Please see the screenshots attached from admin...
