What is the problem with these lines of code?

I would recommend trying to add an output buffer. I find a lot of times if I’m echoing something in WordPress and it doesn’t show up, adding the output buffering does the trick.

<?php

add_action('woocommerce_archive_description' , 'sample' );

function sample(){
    ob_start();
    echo "Hello World";
    return ob_get_clean();
}

?>