One of the challenges facing both students and instructors is keeping track of all of the assignments planned throughout the term. Instructors are teaching multiple courses and students are learning in multiple courses. Every course has its own timeline for when things need to be done. The Calendar helps everyone stay on schedule and up to date.
The Calendar in Canvas is a global feature, meaning users can see all courses assignments and events in one place. Calendars can be filtered by selecting or deselecting courses in the sidebar.
To help manage user calendars, courses customized in the courses drop-down menu as a favorite course will always be listed at the top of the user’s calendar list in the calendar sidebar. By default, the Calendar displays a maximum of 10 course calendars.
From Canvas Basics Guide > What is the Calendar?