If the admin user deactivates the plugin, it asks whether to keep customer portal settings, pages, and configured menus or not.
If the checkbox is checked, the plugin will be removed but data, pages, and portal settings will be kept as it is in WordPress else the plugin will be removed with data, pages, and portal settings when the user deletes the plugin after deactivation.
So, if the admin user needs to deactivate the plugin temporarily but does not want to lose their settings then they can choose this option.