Short answer
A Group team scheduling page shows time slots where all selected team members are available. HubSpot's KB says it needs Sales Hub or Service Hub Starter, Professional or Enterprise and a Sales or Service seat. HubSpot checks the page's availability against each member's connected calendar. The user who creates a group page cannot be removed from it, and the organizer cannot change after creation.
1. Where
Scheduling pages live in Meetings Scheduler. My demo portal:

2. Owner rules
- If the contact's owner is on the page and busy, no times show.
- If the owner is not on the page or has no seat, all members' availability shows.
3. Related
For spreading meetings across a team instead, see round robin.