Overview: 

You can subscribe to calendar items in all your courses and have them appear in your calendar. You can only view the calendar, not make edits to it. 

To add to your Google Calendar: 

1.  Log into Canvas
2.  Navigate to the Calendar
3.  Select Calendar Feed and copy the link provided
4.  Open your google calendar and navigate to  Other Calendars. 
5.  Click on the + and choose From URL
6. Paste in the URL provided in Canvas
7. Click Add Calendar