Arrays are a pretty basic concept in Perl and any other language. Someone who needs this tutorial may also need help with concepts like scalar context and when it's implied.

I usually don't like something like this:

$count = @array;

It works, and it's clear, but mostly because of the variable names. Sometimes I've seen something more like:

$stuff = @things;

In that case, I think someone wrote a bug. It's clear what's meant if the scalar context is made explicit like so:

$stuff = scalar @things;

Otherwise, I have to read (perhaps a lot) more code to see how the variable is used and whether that makes sense, given its origin. When the scalar context is explicit, I can tell right away that the programmer really meant what was written.