In odoo-9 every admin having many types of right to give permission of all users and manager.
And Access rights are defined as records of the model ir.model.access.
For example you can see below code->
And manually you can see below steps-> Step-1 Settings ->user-> users
Step-2 Create a new group session_read through Settings -> Users -> Groups, it should have read access on the Session model
Step-3 Edit demo make them a member of session_read
Step-4 Log in as John Smith to check the access rights are correct