Appointments is a feature with extensive customization options that allows customers to make appointments with you through a mobile app.
The application is designed to be flexible enough so that it can handle any enterprise work flow.
- Customers and appointments management.
- Services and providers organization.
- Working plan and booking rules.
- Google Calendar synchronization (planned)
- Email / Push notifications system.
This feature will be expanded gradually with new features and additions. 
The settings documentation is here: 
Managing Content