With Manual availability enabled, you tell the system how many jobs to schedule per slot you offer.
To Enable:
Go to Settings > Subdomain Tab > Scroll down to Schedule Availability Mode Section
Click Manual
Click Save at the bottom of the page
Once enabled, you will create your booking spots that customers can book.
Go to Settings > Booking Spots > Maximum Settings Tab
This is where you decide which days you will be open for business and what time slots are available each day. This is your default availability that your customers will be able to select when booking.
The Max number of jobs assigned per slot will be the max number of new bookings the system will allow to be booked per day and per time offered
Read more about Booking Spots and their set up here.