What are helpers in laravel code example

Example 1: laravel helper

use Illuminate\Support\Str;

$length = Str::length('Laravel');

// 7

Example 2: how to share a helper globally laravel

<?php
function getDomesticCities()
{
$result = \App\Package::where('type', '=', 'domestic')
    ->groupBy('from_city')
    ->get(['from_city']);

return $result;
}