wp_list_pages
allows you to include a walker function. That would give you complete freedom to add any classes you want, but it’s no a beginner’s method. You could start by reading this.
If you want a simple search and replace on the class, as your question seems to indicate, you can use the wp_list_pages
filter like this:
add_filter ('wp_list_pages','wpse241119_replace_class',10,3);
function wpse241119_replace_class ($output, $r, $pages) {
$output = str_replace ('page-item number', 'hvr-underline', $output);
return $output;
}