bbPress.org

Thank you @lynq for the initiative writing this up 🙂

If you like to show the sub-forum description you could use get_post() and modify the code from @lynq to fetch it.

Something like this:

$get_sub_desc = get_post( $sub_forum->ID );
$show_sub_desc = $get_sub_desc->post_content;

then add $show_sub_desc to the output.