That's because you can't copy and paste the entire thing as a .pl file and expect Perl to understand. Here's what you need to have as the contents of the .pl file:

#!/bin/perl
@type = (
    "Empty", "Run Lvl", "Boot", "New Time", "Old Time", "Init" +,
    "Login", "Normal",  "Term", "Account"
);
$recs = "";
while (<>) {
    $r ecs .= $_;
}
foreach ( split( /(.{384})/s, $recs ) ) {
    next if length($_) == 0 +;
    my ( $type, $pid, $line, $inittab, $user, $host, $t1, $t2, $t3, $t
+4, $t5 ) =
      $_ =~ /(.{4})(.{4})(.{32})(.{4})(.{32})(.{256})(.{4})(.{4})(.{4}
+)(.
+{4})(.{4})/s;
    if ( defined $line && $line =~ /\w/ ) {
        $line =~ s/\
x00+//g;
        $host =~ s/\x00+//g;
        $user =~ s/\x00+//g;
        printf(
            "%s %-8s %-12s 
+%10s %-45s \n",
            scalar( gmtime( unpack( "I4", $t3 ) ) ),
            $type[
              unpack( "
I4", $type )
            ],
            $user,
            $line,
            $host
        );
    }
}
printf "\n"
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The next step after saving your .pl file is to make it executable using the chmod command. A chmod u+x,g+x,o+x wtmp.pl will do it. Then you can run the script like so:

./wtmp.pl
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The above assumes that wtmp.pl is in your current directory.