Publishing Your Canvas Course
Canvas courses and content within them must be published in order to be visible. This article shows you how to publish your course.
How to Publish the Course
The course is now published. You only need to publish the course once. It remains published unless/until you unpublish it.
Publishing Course Materials
Publishing (and leaving unpublished) allows you to control the student view of your course contents.
Unpublished individual items within your course won't be visible. (Example A)
If a module isn't published, none of the published items within it will be visible. (Example B)
When in doubt, publish.
To see which items in your course are visible, you can always use Student View.