Billing rates are the amounts you charge for services. These rates are organized into tables, so you can charge different clients different amounts for the same service items by applying different billing rate tables.
Billing rate tables are further organized into Billing Rate Groups, groups of similar tables, so when billing you can search through a subset of your billing rate tables instead of the whole long list of tables. Set up groups first, then rate tables. Refer to the Rates setup workflow for the complete setup order.