Tasks that have start date or due date set are visible in the calendar. You can drag and drop to move tasks around or drag to change the start or end date. You can always change the dates from the project board. All your archived tasks are also visible in the calendar.
Click on the task to change its name, dates, assigned it to people or view it in the project board.
You can create tasks and assign them to people directly from the calendar view.
You can also set start date and end date automatically by selecting a range in the calendar.