What exactly do the array_keys and array_values functions do?

The `array_keys()` function in PHP returns all the keys of an array as a new array. It takes an array as an argument and returns an array of keys.

Example:

$array = array('key1' => 'value1', 'key2' => 'value2');
$keys = array_keys($array);
print_r($keys);

Output:

Array
(
    [0] => key1
    [1] => key2
)

The `array_values()` function in PHP returns all the values of an array as a new array. It takes an array as an argument and returns an array of values.

Example:

$array = array('key1' => 'value1', 'key2' => 'value2');
$values = array_values($array);
print_r($values);

Output:

Array
(
    [0] => value1
    [1] => value2
)

Both of these functions are useful for manipulating arrays in PHP.