These are indicating Softr User Groups for the template you chose, which allow you to set visibility settings within your Softr app. This allow you to define what content specific user groups can see or not see. So for example, if there is a block or page you only want admins to be able to see (such as an invoice page), you can set that User Groups. The dropdown you are showing us here is just a way to view the app as a specific User Group.
You can check out this video for a guide, however please note the editing feature is changing as of today as we are releasing action buttons in a few hours. But this video should still help explain the purpose of user groups.