Hi vesta,
Take a look at the calendar template in Numbers. The image below is of the one month calendar initially presented by the version of that template included with Numbers 3.
I've included only the first two rows of the calendar grid in this screen shot and the one that follows.

Changing the calendar to show a different month (and year) is a simple matter.
The cell containing the Month name is a popup menu, from which you choose the month.
The cell containing the year number is a stepper cell, whose value is changed by clicking the stepper controls seen to the right of the selected cell.
Those are the only values that need to be changed by the user. Everything else is calculated by Numbers.

As seen in this Print setup view, the month's calendar is scaled to fit on a US Letter size page. In regions using A4 size paper, I suspect the provided template has been resized to fit that page size.

Regards,
Barry
PS: Just took a look at the Calendar app, as recommended by Chris above.
Pressed command-P to open the print dialogue and take a look at the thumbnail of the printed page.
Very similar to the Numbers version:

B.