Read and write is permission Given to the user.
User is allowed to use functions of respective Role.

For Example
If Institute admin 'ABC' logged in as 'Institute head' then 'ABC' can view permissions on Branch Head/Teacher/Student.If 'ABC' changes role to any other role then 'ABC' can operate that account with changed role.

Read permission : You Can View only.
Write Permission : You can View as well as perform functioning after changing the role