Yes, you show no code, the problem description is very vague, you don't say with what the words are to be 'replaced', and yes, this does smell like homework, but...

c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = 'In the table above, the characters themselves, in the first 
+column, are links to descriptions of characters';
 print qq{'$s'};
 ;;
 my %xlate =
   qw(table tooble  characters croobles  selves others  first second  
+links loonks);
 ;;
 my ($word) =
   map  qr{ $_ }xms,
   join q{ | },
   keys %xlate
   ;
 print $word;
 ;;
 $s =~ s{ ($word) }{$xlate{$1}}xmsg;
 print qq{'$s'};
"
'In the table above, the characters themselves, in the first column, a
+re links to descriptions of characters'
(?msx-i: first | selves | table | links | characters )
'In the tooble above, the croobles themothers, in the second column, a
+re loonks to descriptions of croobles'
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Update: Caution: long lines: some wraparound may have occurred.