The Store Pickup + Delivery Breakpoints feature allows you to have two different offsets for each day of the week. This is useful when offering customers the ability to pickup next day if they order before a specific time. But, allowing a longer time if they order afterwards.
Taking the screenshot above as an example. If the customer tried placing an order on a Monday before 2:00 PM then they would be able to pickup the next day from 9:00 AM. If the customer ordered at 2:01 PM then the earliest they could pickup their order would be the Wednesday at 3:00 PM.