Canada Day is the national day of Canada, a federal holiday celebrating the anniversary of the July 1, 1867, enactment of the Constitution Act, 1867, which united three colonies into a single country called Canada. Canada Day observances take place throughout Canada as well as internationally. Canada Day is the equivalent of our (US) July 4. Since July 1 is on Sunday, Monday will be a national holiday.
Here's the National Anthem.