If the POD explanation isn't enough, it wasn't for me having never used sed or awk to any great extent, then this might clarify things.

perl -e"open ARGV,'<',$ARGV[0]or die $!; while(<ARGV>){ print if $. >=
+15 and $. <=17 }" file
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This is (roughly) analogous to the one-liner you showed except it will only handle a single input file. The open and while parts are performed for you by the -n command line switch. See perlrun for details.

The 15 .. 17 is (roughly) equivalent to the if condition above.