Desktop application, or mobile application.
Allows the user to log in.
2. creation of customer database on the basis of a completed form.
2. daily hourly planner in the form of columns (depending on the number of employees).
3. possibility of booking services (specifying their time).
And many others. This is a complex project and in the future it will need a permanent maintainer or even several to keep improving it and keep it under supervision.
He wants to create an application along the lines of the existing one.