you are initializing @employees as an array containing a
single element, which is an anonymous array. the
initialization should read:
my @employees = ();
this will initialize it as an array with no elements.
More specifically, the original code could be written this way:
my $employees = [];
Hopefully that makes it clear that a list enclosed in square brackets is an anonymous list. Assigning that somewhere creates a reference. (That's why you can stuff it in a scalar.)
The original code creates @employees and sets the first (and only) element to a reference to that anonymous list.