You can copy and paste a calendar into a slide but you can’t edit the calendar after as it becomes a picture. However, just as you can with any picture, you can resize and crop the calendar.
Find and select the calendar that you want to paste into PowerPoint, and then on your keyboard press Print Screen.
In PowerPoint, on the Insert tab, click Screenshot, and then select the calendar screen shot.
Tip: Check out the free calendar templates on office.com.