This feature is only available to Admins
By default, each organization starts with a People entity type. For many organizations, people are going to be the only thing you're organizing and if that's the case then you don't need to worry about creating a new entities. However, some organizations may decide to organize around things that are not people. Examples of this might be Contractors, Subcontractors, Job Sites or Business if you're organizing a labor campaign. Other groups might be organizing a group of like-minded organizations and want to create entities for Non-Profits or Churches. All of that is possible with entity types.
To create a new entity type, go to the three dots in the top right and select Entity Types:
To add a new entity type, select + Add New Entity Type. In the pop up, enter the Plural and Sigular names for this type of entity and check/uncheck the boxes that are relevant for the entity (for instance, some entities might not need a preferred language, or have a physical address. In those cases, you can uncheck the box and those options will be removed when adding that entity type to your campaigns). Make sure to select Create Entity Type once you're done:
You can also edit any existing Entity Types by clicking on the arrow next to the entities name. From there you can check/uncheck any options for the entity, manage which campaigns have access to the entity and Manage any Info Field related to that entity type.