In the three participating provinces, provincial government offices are closed but federal offices, like Canada Post, for the most part are open. School is out and libraries are closed but shopping malls, popular attractions and restaurants stay open to give families stuff to do .
Openings and closings are not an exact science, so call or check websites to make sure. Read more about what's open and closed Family Day
For more information on the holiday, check the government website for your province.