$ cat HoH.pl 
#!/usr/bin/perl -w
use strict;
use Data::Dumper;
require 'hash';
print Dumper(%HoH);


$ cat hash
my $HoH = {
         'HASH_1' => {
                item_a => "abc",
                item_b => "123",
                item_c => "blue",
        },
        'HASH_2' => {
                item_a => "xyz",
                item_b => "789",
                item_c => "white",
        },
        'HASH_3' => {
                item_a => "ijk",
                item_b => "3.14",
                item_c => "yellow",
        }
};


$ ./HoH.pl 
Global symbol "%HoH" requires explicit package name at ./HoH.pl line 5.
Execution of ./HoH.pl aborted due to compilation errors.