@{$h}{qw{month year day first_name}} = delete @{$h}{qw{mm yyyy dd name}};

C:\@Work\Perl>perl -wMstrict -e
"my $h = { mm => 'July', yyyy => '1975', dd => '31', name => 'Milo', last_name => 'Manara',};
print qq(o/p: \n);  print qq($_ => $h->{$_} \n) for keys %$h;
@{$h}{qw{month year day first_name}} = delete @{$h}{qw{mm yyyy dd name}};
print qq(-----\n);  print qq($_ => $h->{$_} \n) for keys %$h"
o/p:
mm => July
name => Milo
dd => 31
last_name => Manara
yyyy => 1975
-----
month => July
day => 31
first_name => Milo
year => 1975
last_name => Manara