In a situation like this, a hash is just the ticket.

You haven't given any sample data, but here is an example of how you could do it using the last few lines of your question as the "@words"

#!/usr/bin/perl -w
use strict;
use Data::Dumper::Simple;

my @words =  qw(to check now across my string whether any elements in 
+my string are repeated,
and if so, how many times. I've read alot about manipulating arrays, b
+ut
they're all based on arrays that you create yourself, rather than arra
+ys
created by opening a textfile, so I'm not sure how to manipulate my ar
+ray.
Any help would be much appreciated.);

my %unique_words;

for (@words) {
    $unique_words{$_}++;
}

print Dumper(%unique_words);
[download]

The above will print each unique "word", and how many times it appears.

Cheers,
Darren :)