Collection Permissions allow you permission not only on tools users have access to but also on data points. For example, if you have a volunteer user level who should not see sensitive donation or voter data about any profile collection permissions allow you to tailor that view.
You can edit which field collections user levels below you have access to. To start, go to Settings > User Settings > User Levels. Then select the pencil icon to edit a user level.
Scroll down to the bottom of the User Level edit page until you see the box that says "Profile Permissions." Select "Custom" from the drop-down to edit the permissions for any of the tabs. Then, click the gear icon to customize what field collections per tab you grant or deny to each user level.
Next to any profile field collection, you will see a drop down for that user level to "Edit and View," "View," or "None." Select which one you would like. You can also check the box if you want the selected user level to be able to assign this to user levels below this user level.
Once you have finished customizing the profile field collection for a user level click "Done." Then, click "Save" to save the changes you have made on the next page.