Let me start with the most obvious issues:

• The lines

      %file2 = 'Source.txt' ;
      open(INFO, "<%file2" ) ;
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  is incorrect. You should use a '$' here, not a '%', since file2 is holding a simple string. For that matter, you could reuse $file1 from the previous block of code, or do without storing the filename in a variable altogether:

      open(INFO, '<Source.txt');
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• You're not verifying that any of the open() calls succeeds.
• You're not removing end-of-line characters from any of the lines you're reading.
• You're comparing strings containing only IP addresses (from the first file) to strings containing IP addresses and country names (from the second file). You're unlikely to find any matches.

I would be inclined to use a hash to store the table of IP addresses and countries. You'd construct the hash something like this:

    my %table;
    open(IN, '<Source.txt') or die;
    while (<IN>) {
        chomp;
        my($ip, $country) = split(' ', $_, 2);
        $table{$ip} = $country;
    }
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You'll have to make sure that split() call correctly splits your input data into IP and country name, of course.

Once you've done that--and assuming you've removed newlines from your input data--you can do country lookups like this:

    open(OUT, '>>conversion.txt') or die;
    foreach $line1 (@lines1) {
        if (exists $table{$line1}) {
            print OUT $line1, ' ', $table{$line1}, "\n";
        }
    }
    close OUT;
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