Copy this section from include/theme.inc.php at about line 4398:
/******************************************************************************
** Section <<<theme_album_info>>> - START
******************************************************************************/
// Format information which is displayed next to each album
function theme_album_info($pic_count, $link_pic_count, $last_upload_date)
{
global $CONFIG, $lang_list_albums;
if ($CONFIG['link_last_upload']) {
$album_info = sprintf($lang_list_albums['n_pictures'], $pic_count) . (($CONFIG['link_pic_count'] && $link_pic_count > 0 ) ? sprintf(", {$lang_list_albums['n_link_pictures']}, {$lang_list_albums['total_pictures']}", $link_pic_count, $pic_count + $link_pic_count) : "") . (($pic_count || ($CONFIG['link_pic_count'] && $link_pic_count > 0 )) ? sprintf($lang_list_albums['last_added'], $last_upload_date) : "");
} else {
$album_info = sprintf($lang_list_albums['n_pictures'], $pic_count) . ($pic_count ? sprintf($lang_list_albums['last_added'], $last_upload_date) : "") . (($CONFIG['link_pic_count'] && $link_pic_count > 0) ? sprintf(", {$lang_list_albums['n_link_pictures']}, {$lang_list_albums['total_pictures']}", $link_pic_count, $pic_count + $link_pic_count) : "");
}
return $album_info;
}
/******************************************************************************
** Section <<<theme_album_info>>> - END
******************************************************************************/
and place it in your theme's theme.php file. Then modify as needed.