The function first_value (from List::MoreUtils) is slightly better than grep because it returns the single value that you expect as a scalar.

use strict;
use warnings;
use List::MoreUtils qw(first_value);
my(%DetailSheet) =    (
    ...
    );

my %Column = %{$DetailSheet{ColumnName}};
my $description = first_value {$Column{$_}{XlsColumn} == 2} keys %Colu
+mn;
print $description, "\n";
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