Block "Template available for" provides "visibility" of the document through the application.

 
This template will be available for the deals and invoices.
Depending on the type of object, will form the drop-down menu for the template editor.

Only for business process: this option avoids the formation of the document in the application context. If this checkbox is checked, the document will be created only within a business process.

By default, any template is available for all users.
You can provide access for some employees. For the rest of the staff this template will be invisible.