How to generate a random number

Short answer

random_int() returns a random integer; both bounds are inclusive:

<?php
 
echo random_int(1, 100);

A random array element

array_rand() returns a random key of the array:

<?php
 
$colors = ['red', 'green', 'blue'];
 
echo $colors[array_rand($colors)];

Shuffling an array

shuffle() reorders the elements of the array itself at random:

<?php
 
$cards = [1, 2, 3, 4, 5];
shuffle($cards);
 
echo implode(', ', $cards);