You can use the Data::Table::Excel module to put the contents of a Data::Table object into an Excel file. From the documentation,

This perl package provide utility methods to convert between an Excel file and Data::Table objects. It then enables you to take advantage of the Data::Table methods to further manipulate the data and/or export it into other formats such as CSV/TSV/HTML, etc.

For example, this code will create an xlsx file that contains both the mean and stddev tables:

#!/usr/bin/env perl

use strict;
use warnings;

use Data::Table;
use Data::Table::Excel qw(tables2xlsx);
use Statistics::Lite qw(mean stddev);

my $dt = Data::Table::fromCSV("data.csv");
my $melt = $dt->melt(['Month', 'Zone', 'Replicate']);

my $cast_mean = $melt->cast(
    ['Month', 'Zone'],
    'variable',
    Data::Table::STRING,
    'value',
    \&mean
); 

my $cast_stddev = $melt->cast(
    ['Month', 'Zone'],
    'variable',
    Data::Table::STRING,
    'value',
    \&stddev
); 

tables2xlsx("descriptive_stats.xlsx", [ $cast_mean, $cast_stddev ]);

exit;
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