Issue with Roles module API's

Hi Team, I am not able to do any operation on "Roles" module. 

Do we have access to retrieve "Roles" module properties / fields ?

When I try to access its properties through Postman using
api call it throws below error - 


    "modules": [],




Do this module "Roles" has no properties in v11_21 latest api version ? 

Please guide me on above queries, as I am not able to perform CRUD operations on this module.