Can anyone explain what is AdSense for Domains and how to use this any pro's and con's? I have no idea about this
Adsense for domains are their premium brand of ads for domains, it's basically domain parking only with adsense. Your site has to be of quality and meet their criteria, they monitor what kind of traffic you send and the payout avg cpc is alleged to be less than regular adsense. I got in with a domain and it doesn't convert that well, you're better off with another parked monetization provider. But if you prefer adsense and the google brand you can try it out, it requires having an adsense account in good standing (meaning not suspended).
I also tried it with very very poor results. You should use it with either a domain that get traffic because it's a premium name and people enter it directly in their browser, or because it's an old domain with still lots of backlinks pointing to it from other sites. Otherwise it's a waste of time to set it up, I've lost about 30 minutes on doing it since it was the first time, and it'll be the last time too!