The Multiple Checkboxes attribute allows you to select multiple values by checking off checkboxes.
Values for the checkboxes are created in the Values tab when creating the attribute.
Multiple Checkboxes using data from an App API call
The Multiple Checkboxes using data from an App API call attribute allows you to pull in data from another app by using an API call that is set up when the attribute is created. This info that is retrieved by the API call can then be used in your content.
An example scenario could be to associate certain profiles from the Directory app with a page to display their bios automatically on that page.