array fill key use in php project

$arrays = [[1, 2], [3, 4], [5, 6]];
 
foreach ($arrays as list($a, $b)) {
    $c = $a + $b;
    echo($c . ', '); // 3, 7, 11, 
}

// define array
$array = ['a', 'b', 'c'];
 
// without list()
$a = $array[0];
$b = $array[1];
$c = $array[2];
 
// with list()
list($a, $b, $c) = $array;

$string = 'hello|wild|world';
list($hello, , $world) = explode('|', $string);
echo("$hello, $world"); // hello, world