Mainframes have both online and batch systems.
In online systems, there are screens with menus. In a few scenarios, the team has to login to legacy online systems (like CICS), select a few options in the screens and update particular fields and save it. For e.g. update a flag by navigating the screens and log out from the system.
Finally, they send a mail to business users after updating the legacy systems.
These login and navigation to multiple screens can be automated.