Paste the following code in functions.php:

/* Add text under products in shop */
add_action( 'woocommerce_after_main_content', 'my_text', 5 );
function my_text() {
  if( is_shop() ) {
    print '
Your text here
'; } }

Edit text (in “print”) as needed.

Source: https://wordpress.org/support/topic/add-text-to-shop-page/