Usage of do_action and add_adction

I’m trying to use add_action to add HTML output to a plugin’s front end area,
Below is the snippet from plugin

<ul class="dashboard-links">
    <li><a href="https://wordpress.stackexchange.com/questions/300750/<?php echo $dashboard_links["commissions'] ?>"><?php _e( 'Commissions', 'yith-woocommerce-affiliates' ) ?></a></li>
    <li><a href="https://wordpress.stackexchange.com/questions/300750/<?php echo $dashboard_links["clicks'] ?>"><?php _e( 'Clicks', 'yith-woocommerce-affiliates' ) ?></a></li>
    <li><a href="https://wordpress.stackexchange.com/questions/300750/<?php echo $dashboard_links["payments'] ?>"><?php _e( 'Payments', 'yith-woocommerce-affiliates' ) ?></a></li>
    <li><a href="https://wordpress.stackexchange.com/questions/300750/<?php echo $dashboard_links["generate_link'] ?>"><?php _e( 'Generate link', 'yith-woocommerce-affiliates' ) ?></a></li>
    <li><a href="https://wordpress.stackexchange.com/questions/300750/<?php echo $dashboard_links["settings'] ?>"><?php _e( 'Settings', 'yith-woocommerce-affiliates' ) ?></a></li>
    <?php do_action( 'yith_wcaf_after_dashboard_links', $dashboard_links ) ?>
</ul>

I’m trying to extend it by adding the snippet written below in functions.php

function add_link_to_aff() {
    $html_output =  "<li><a href="#"><?php _e( 'Test', 'yith-woocommerce-affiliates' ) ?></a></li>";
    return $html_output;  
}
add_action( 'yith_wcaf_after_dashboard_links', 'add_link_to_aff', 10 );

This is the snippet which I’m g, I also tried passing $dashboard_links to the function but it didn’t worked.

You need to echo your data. Try this instead –

function add_link_to_aff() {
    $html_output =  "<li><a href="#">" .  __( 'Test', 'yith-woocommerce-affiliates' ) .  "</a></li>";
    echo $html_output;  
}
add_action( 'yith_wcaf_after_dashboard_links', 'add_link_to_aff', 10 );