my %hash;
open (FILE,"abc.txt");
while (<FILE>)
{
   chomp;
   my ($key,$val) = split '\|';
   print $hash{$val};
}
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Almost there:

use strict;
use warnings;

my %hash;
open my $fh, '<', 'abc.txt' or die $!;
while (<$fh>) {
    chomp;
    my ($key, $val) = split '\|';
    $hash{$val}++;
}

print "$_\n" for sort keys %hash;
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