I understand that as "document every class/module/public method with javadoc/pydoc/whatever and also explain the (few!) counter-intuitive bits of your code with inline comments. (You might find those deep within an algorithm, but usually not in plumbing or business logic code)."

That should leave you with a solid documentation of your application's components and APIs and a small amount of inline comments.

If you find you have more comments, either your code should be simplified or you're commenting trivialities.

As everything, it's a guideline with exceptions, not an absolute rule.