Google has launched an algorithmic change that looks at the layout of a webpage and the amount of content you see on the page once you click on a result.

They heard complaints from users that if they click on a result and it’s difficult to find the actual content, they aren’t happy with the experience. Rather than scrolling down the page past a slew of ads, users want to see content right away. So sites that don’t have much content “above-the-fold” can be affected by this change. If you click on a website and the part of the website you see first either doesn’t have a lot of visible content above-the-fold or dedicates a large fraction of the site’s initial screen real estate to ads, that’s not a very good user experience. Such sites may not rank as highly going forward.
But affects sites that go much further to load the top of the page with ads to an excessive degree or that make it hard to find the actual original content on the page

How do you define “above the fold”?

Check here is your site or sites meets the criteria about and where is the fold.