Providers are people that you can set up on your calendar to be booked for services. Often they are staff members, employees, or teammates. In a minority of cases, they may not be people. For example, sometimes a conference room can be set up as a provider because it gets booked out.
How to set up a provider
A Provider can be added to a calendar by clicking on the Provider menu option, then select "Add." If it's a staff member, employee, or teammate, you can grant them calendar privileges.
If you've granted someone calendar privileges, that person will be able to book, cancel, and message customers the same way the calendar owner can. The only things that person won't be able to do is change calendar settings, adjust payment processing, or affect calendar sharing settings.