Getting Check Box name as array[] and values

<td><input class='checkBoxes' type='checkbox' name="checkBoxArray[]" value="<?php echo $post_id; ?>"></td>
  

<?php 

if (isset($_POST['checkBoxArray'])) 
{
  foreach($_POST['checkBoxArray'] as $checkBoxValue)
  {
    echo $checkBoxValue;
  }
} 

?>

I gave the checkbox name as checkBoxArray[] and i have made post_id as a loop from the database.And I want to know how it is fetched as an array with values when we still keep it as empty in the name checkBoxArray[] , How it is fetched explain me the whole process please