How to Change Placeholder text of Zip code at Cart page

The clicked field comes from your locale-based JavaScript and may be quite difficult to change. The unclicked field should be changeable with this code:

<?php
  // Change default checkout fields placeholders
  // code goes in functions.php for your child theme
  add_filter('woocommerce_checkout_fields', 'custom_override_placeholders')
  function custom_override_placeholders($address_fields) {
    $address_fields['postcode']['placeholder'] = 'postcode';
    return $address_fields;
  }

However, a user from another locale may see something different.