One of those ways is pictured in the screenshot above which is a reporting feature. It looks pretty standard as far as reporting posts goes, but there is an option for users to select if they think that it is a fake news story. When you select that option, you are given more options where you can block the person sharing the news, inform them, or report it directly to Facebook.
Another way Facebook is combating fake news is through third-party checkers. Posts that contain fake news (or may contain fake news) will be highlighted to the user and lets them know that third-party fact-checkers have deemed this story to be fake. You can still read it, comment on it, or share it, but you have been warned.
Last but not least, there is the financial incentive which will be removed by Facebook. This is something the company has done earlier which is by removing access to Facebook’s ad network. This means that publications that spread fake news will no longer receive revenue from ads, which will hopefully reduce the amount of posts they make.