He is talking about building as many sites as possible (free or paid for), with lots of content, and adsense included. There is no secret to that: Build as many sites as possible, with content that will show up in search engines, and hope someone comes there to click your adsense ads. I prefer quality, over quantity though. If your adept at multiple site building, all the power to you.
Provided the free host doesn't cut off your traffic after a given amount in a day, then it makes no difference if it's a free host or a paid host I have several paid for, add-on hosting accounts that are worse than some of the free hosted accounts I have I get 1,200 to 1,600 visitors a day to each of 2 of my free hosted accounts - I know it's way short of what the originator of this thread is claiming - but just because it's a high number doesn't mean it's fake
I also curious how you get this good adsense income because i am now struggling to earn cents per day.
There are two ways: 1/ Create good original content on a niche site, backlink the site's pages, hope and pray for large volumes of Google traffic 2/ Realise that if you can get enough web pages onto the Internet by whatever means you have at your disposal, then large numbers of people will see your adsense ads, and a percentage of them will click your adsense ads - i.e. quantity over quality