In the properties of each task, you can choose a due date and time. It is recommended to fill in this field, so your tasks that are scheduled for today show up in the My Day section. The same goes for tasks that have due dates in the next 7 days. They are shown under My next 7 days.
Using due dates makes it possible to group, sort and filter your tasks based on their due date.
Also, if you prefer the calendar view, scheduled tasks are shown on their due dates.