You can add as many categories as you want.
To add a call category, click your name in the top right of any Gong page and go to your company settings.
Under Optimize Analysis, click Categories. Scroll down and click ADD NEW CATEGORY.
Hove the default category name to show the edit icon, and then give the category a new name.
To choose which calls will be in the category, hover the All Calls label and click Change. This opens the filter dialog, the same dialog you see on the Search page. For more details on call filters, see this.
You can also add categories from the INSIGHTS > Team page. Click on the Category field in the top right corner to open the dropdown menu and click +Add a category at the bottom.