Learn

Hashes are unordered key-value collections:

my %ages = (
    alice => 30,
    bob => 25,
    carol => 40,
);

print $ages{alice}, "\n";        # 30 — $ sigil for one element
$ages{dan} = 50;                 # add
delete $ages{bob};               # remove
exists $ages{alice};             # true (defined and present)

my @keys = keys %ages;           # all keys
my @vals = values %ages;

for my $name (sort keys %ages) {
    print "$name: $ages{$name}\n";
}

The => ("fat arrow") is just a fancy comma that auto-quotes the left side. So (alice => 30) is the same as ("alice", 30).

Hashes are how you build records, lookups, counters, and most non-trivial data:

my %word_count;
$word_count{$_}++ for split /\s+/, $text;

That's a complete word counter — split on whitespace, increment hash entry per word.