The 'User Is In Any Users' will verify that the current user is one of the selected users.
You must specify the allowed users, when configuring the check. For example:
For information on how to configure a condition for a workflow transition in JIRA, see the JIRA documentation.
A workflow is configured so that the 'Automation' transition has the 'User Is In Any User' check = 'jsu-technical-user' user only. This is a user account which does not belong to a human person, but is used for all kind of automations. It has more permissions than normal users, so automations can do things which would be restricted for normal users.
A normal user viewing an issue in that workflow will not see the 'Automation' transition.
This is a perfect use-case to hide a Transition which will be triggered by a 'perform as user' (impersonate) Post-Function. So you configure also 'jsu-technical-user' as the 'perform as user' in the Post-Function.
Only the boss
You might restrict some transitions in your workflow to the big boss and his deputy.