A ping is when you send a message to your external feed porvider such as feedburner or bookmarking sites that you have updated your content and that they should come and re-index it.
But when your site/blog has so many sites that are bookmarking it it becomes difficult going to each site and requesting a ping but there is now an easier way to do it.
This can be done using sites such as pingomatic that all you have to do is input your website/blog url and then select the sites that are bookmarking your site and then the website will do the rest saving you alot of time and effort.
