Account Groups are an extremely important part of your World Manager platform and are used to create your Account Hierarchy.
Once an account group is created at world-level, each country can have their own (bespoke) names for them. You even have the option to disable groups (if not required).
With different functions and permissions available for each of the different Roles, making sure the Account Groups are set up properly will go a long way to ensuring you're able to manage your content effectively.
For a comprehensive look at the platform's hierarchy, please check out the below video.