$ perl -Mstrict -Mwarnings -le '
# Braces denote an anonymous hash
my $owner1Ref = {
    "name" => "Santa Claus",
    "DOB"  => "1882-12-25",
};

my $owner2Ref = {
    "name" => "Mickey Mouse",
    "DOB"  => "1928-11-18",
};

# Square brackets denote an anonymous array
my $ownersRef = [ $owner1Ref, $owner2Ref ];

my %account = (
    "number" => "12345678",
    "opened" => "2000-01-01",
    "owners" => $ownersRef,
);

print $account{owners}[0]{name};
'
Santa Claus