Meaning you can switch between the old appointment slots and the new appointment schedules at any time. Right now, old appointment slots and new appointment schedules can co-exist on your calendar. These will eventually replace appointment slots but there’s no date just yet for when the switch to appointment schedules will be made.
Within these account types Appointment Slots are the default selection, however appointment schedules can be turned on. These include Workspace Individual, Business Standard and Above, Enterprise and Education accounts. They’re only available to those on a paid plan on Google Workspace. It’s important to mention that these features are not available on free workspace plans or accounts.