what is blog pinging?

Well, think it like this when you are on facebook and if you are seeing that your firend is online and you want to start a chat then what you do at first is saying "hi" in the chat box which means pining to know wether he's available or not ! So, I guess now you can draw the idea what pining is !

Pinging in SEO is informing search engine about the latest changes you have made in your blog/ website.

There are many pinging tools by which you can inform search engine to crawl and index your new web pages.

Google’s Blogger service, often referenced to by its Blogspot domain, provides organization owners with many alternatives for promoting their blogs and informing the public about blog updates, a process known as "pinging."

@harrykingsville you can try using pingomatic tool its a good tool.

@harrykingsville There are many Pinging tools available as you can just search it on the web.
Here are a few:
pingomatic.com
twingly.com
auto-ping.com
feedshark.brainbliss.com
mypagerank.net
icerocket.com
blo.gs
bitacoras.com
totalping.com
ping.in
Hope this might be useful for better indexing of your blogs.

i think the best way to inform googl eabout changes to your website is using google craw tool in webmaster tools

In simple language Blog pinging means send a crawling request to google spider.