Sort is very powerful and customizable. With sort you can create your own sub routine to determine how an array is sorted. Your subroutine will get two elements of your array as $a and $b. Your return code will determine how the array will be sorted.
-1 -- $a comes before $b
0 -- $a and $b are equal
1 -- $b comes before $a
Below is an example of how to sort on two keys:

@a = ( ["oops", 1], ["oops", 0], [ "happy", 2 ], [ "word", 4 ] );

@a = sort my_sort @a;

foreach $ar (@a) {
    print "$ar->[0] is $ar->[1]\n"
}

sub my_sort {
    # Lets first compare element 0
    if ($a->[0] lt $b->[0]){
        return -1;
    }
     if ($a->[0] gt $b->[0]){
        return 1;
    }
    # Element 0 is equal, let now compare element 1
    if ($a->[1] < $b->[1]){
        return -1;
    } 
    if ($a->[1] > $b->[1]){
        return 1;
    }
    # Both elements are equal
    return 0;
}
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Note, this code is not necessarily the best way to do this, it is provided to show some theory behind sort.