footer.php vs wp_footer()

What does wp_footer() do? It exists in the footer.php file (I’m using a starter theme, _s) but does not appear to add anything to the page. I looked up the function, but the code is simply:

function wp_footer() {
    /**
     * Print scripts or data before the closing body tag on the front end.
     *
     * @since 1.5.1
     */
    do_action( 'wp_footer' );
}

What “scripts or data” does the comment refer to?