I would also like to know how I could make a new hash out of this one that has [? the value of ?] "ScreenName" as the $key and "Description" . " " . "Type" as the elements.

I don't quite understand what you mean by this (you provide no expected output structure as an example (update: see also How to ask better questions using Test::More and sample data)), but here's a guess:

Win8 Strawberry 5.8.9.5 (32)  Fri 06/04/2021 21:34:07
C:\@Work\Perl\monks
>perl

use strict;
use warnings;

use Data::Dumper;

my %hash = (
          'ScreenName1.Description1' => {
                     'ScreenName' => 'A',
                     'Description' => 'A Description of this button',
                     'Type' => 'On/Off'
          },
          'ScreenName2.Description2' => {
                     'ScreenName' => 'B',
                     'Description' => 'A Description of this button',
                     'Type' => 'Momentary'
          },
          'ScreenName3.Description3' => {
                     'ScreenName' => 'A',
                     'Description' => 'A Description of this button',
                     'Type' => 'Momentary'
          },
          'ScreenName4.Description4' => {
                     'ScreenName' => 'A',
                     'Description' => 'A Description of this button',
                     'Type' => 'On/Off'
          },
          'ScreenName5.Description5' => {
                     'ScreenName' => 'B',
                     'Description' => 'A Description of this button',
                     'Type' => 'On/Off'
          },

    );

my %ScreenNameValues;

for my $hr (values %hash) {
    $ScreenNameValues{ $hr->{'ScreenName'} }++;
    }

print Dumper \%ScreenNameValues;
print "$_ == $ScreenNameValues{$_} \n" for sort keys %ScreenNameValues
+;

my %ScreenNameDT;

for my $hr (values %hash) {
    push @{ $ScreenNameDT{ $hr->{'ScreenName'} } },
         "$hr->{'Description'} $hr->{'Type'}";
    }

print Dumper \%ScreenNameDT;

^Z
$VAR1 = {
          'A' => 3,
          'B' => 2
        };
A == 3
B == 2
$VAR1 = {
          'A' => [
                   'A Description of this button Momentary',
                   'A Description of this button On/Off',
                   'A Description of this button On/Off'
                 ],
          'B' => [
                   'A Description of this button Momentary',
                   'A Description of this button On/Off'
                 ]
        };
[download]

Update: Also see also Perl Data Structures Cookbook.