Something that a lot of people forget, is the fact that while Google has their hands in all kinds of businesses. Including a mobile OS in Android, an ISP as Google Fiber, a wireless carrier as Project Fi, just to name a few. Google is an ad company. In fact, they make more than 90% of their revenue from ads. Not just from their search results, although that's a big number of their ads, also from other sites that use Adsense. Ads have been in Google search results for a pretty long time, in fact as long as we can remember. There would normally be about 3-5 ads on the right-hand side, as well as three or so above your search results. However, Google has decided to change that up a bit.
Google is deciding to remove their ads from the right side of search results pages. So essentially they are decreasing the number of ads you are seeing, even though they are also adding a fourth ad to the set of ads at the top of the search results page. So instead three up there, you now see four. Google stated that they've "been testing this layout for a long time so some people might see it on a very small number of commercial queries." The company went on to say that they'll "continue to make tweaks but this is designed for highly commercial queries where the layout is able to provide more relevant results for people searching and better performance for advertisers."
While this won't really affect the majority of the internet that performs Google searches, it should help out advertisers and give them better performance. In turn, what that means is that by giving better performance to advertisers, Google will make more money by having advertisers spend a bit more to get even better results. After all, these ads are what pay for Android, Google Drive, and just about everything else that Google offers right now. Many people dislike ads, however they keep the internet free, and with more and more ad blockers popping up, Google has to do something here.