Why it's important? if you don't know about how python module, namespace and packaging in general manner you will die :-).
This section not talk about how to create package, but more general about what is package and module it self.
Good explanations by David, this section also compare which one that should and shouldn't do by developer.
for more information you can watch PyCon 2015 By David Beazley - Modules and Packages: Live and Let Die!