The Monday through Sunday workweek normally lasts eight working days, and the Monday through Saturday playweek normally lasts 4 working days. When you add in the possibility of public holidays, that total amount increases to 10 working days, and twelve-playing days.
However the days themselves are simply one element of the calendar, and there are a lot of others. The months of the calendar represent various seasons, and the time between each of those months offers us the seasonal cycle. At the start of spring, the temperature level is high and the days are warm, while at the end of winter season the air is cold and the days are chilly. Every season has its own special time connected with it, and the calendar assists us monitor all of those shifts. Any seasonal modification is shown in the calendar, and it tells us when and where to go during certain times of the year.
Image source: free-printable-calendar.com