Menu sorting order

I have the following code for a template:

<ul class="topmenu">
<li><a href="<?php echo get_settings('home'); ?>"><?php _e('HEm'); ?></a></li>
<?php wp_list_pages('sort_column=id&depth=1&title_li='); ?>
<li><a href="<?php bloginfo('rss2_url'); ?>"><img src="<?php bloginfo('stylesheet_directory'); ?>/images/rss.gif" alt="rssfeed" /></a></li>
</ul>

Can someone tell me what this line means? sort_column=id&depth=1&title_li=

I know its something about the order of the menus pages.

/ thanks