The hub is a launchpad for the tools you'll use to fix your issue. Each tab has a set of tools to address different types of problems: Select Company File Issues if you have an error message when you open your company file or have missing or blank lists.
QuickBooks Tool Hub is (or should be) your go-to software solution for fixing any QuickBooks Desktop issue. It is actually a collection of tools, each of which has its own specific purpose in the troubleshooting process.