This can be accomplished simply and efficiently using a hash:

#!/usr/bin/perl
use strict;
use warning

my @ldapFields = ("unvLocalPhone", "unvLocalAddress", );

my %field_hash = (unvLocalPhone => "Phone",
                  unvLocalAddress => "Address",
                  );
foreach my $field (@ldapFields) {
    if (exists $field_hash{$field}) {
        $field = $field_hash{$field};
    }
}
[download]

A hash is an associative array of scalars - it associates a scalar key with exactly one scalar value - and is (IMHO) Perl's single greatest feature. If you are unfamiliar with them, a read through perldata would be a good start.