As a Manager, you manage certain user information:
activate and deactivate accounts
reset user's email address or password
upgrade or downgrade accounts (student/teacher/author/manager account)
Then, you can search for the user by their name or email. When you find the user you were looking for, you will see some options next to their name:
Pencil- change user information, reset the password, email, author groups, etc.
Checkmark- deactivate/activate/anonymize the account
Envelope- next time the user logs in, they need to change the email address
Padlock- next time the user logs in, they need to change the password