“wpcfe_before_invoice_content” action hook allow to add additional information on the print invoice template.
Note: This action hook is only available in the Frontend Manager addon plugin. To add the additional information after the invoice template use the “wpcfe_end_invoice_section”.

Copy and paste the following code in the theme functions.php file.
function my_custom_data(){
?>
<div class="my-4">
<h2>Additional Information</h2>
<p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Donec odio. Quisque volutpat mattis eros. Nullam malesuada erat ut turpis. Suspendisse urna nibh, viverra non, semper suscipit, posuere a, pede.</p>
<p>Donec nec justo eget felis facilisis fermentum. Aliquam porttitor mauris sit amet orci. Aenean dignissim pellentesque felis.</p>
</div>
<?php
}
add_action('wpcfe_before_invoice_content', 'my_custom_data');