What exactly is in each array? This works:

use warnings;
#use strict;
use Data::Dumper;

my @array1 = 1..4;
my @array2 = 2..6;
foreach $G (@array1){
    for $x (0..$#array2){
        if($array2[$x] =~ /$G/){
        push(@Coordinates,"$array2[$x]");
        }
    }
} 
print Dumper(\@Coordinates);

__END__
$VAR1 = [
          '2',
          '3',
          '4'
        ];
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See also the Basic debugging checklist