I want to create a role in Drupal. I want create role assign to specific user. Specific user can create only user and not anything.
admin/people/permissions/roles and create your role. Then go to
admin/people/permissions and uncheck all the permission for the new user and check the Administer users permission in the User section:
To uncheck all the permission I can sugest you the use of the Permission Select module.
Permission Select is a module that allows for quicker editing of role permissions on /admin/user/permissions.
And as Pierre Vriens says in his comment:
"do not grant ANY permissions to authenticated users". Because any user with permission to create users is also an authenticated user.
You can create roles in drupal 7 on admin/people/permissions/roles. Then assign the permissions that you want to that role.
There is a permission called "Administer users" but be careful because it can have security implications. Make sure that it only does what the user is supposed to do: test it!
Otherwise you could create your own permission with hook_permission and decide exactly what permission you want to grant.