What does a service desk customer see in the portal?
In the spaces an administrator selects under App Settings > General Settings > Service Management, a request shows the assigned agent's name, a status lozenge and how long the absence lasts.
Portals in every other space show nothing.
Related pages
Agent Availability Display in JSM Customer Portal - where this is covered in full.
Jira Service Management & ITSM - more questions on this topic.