Without getting all techy on you, Microdata (which is just fancy talk for a form of code) has been added to your Facebook pixel to send more data from your website (like specific actions people are taking on your site) back to Facebook. This data will help the algorithm to optimize your ads even better because it will have even more data on the actions visitors are taking when they're on the site (like button activity - purchase, add to cart, and I suspect, time spent on site). It will also include information from your websites metadata to better understand context associated with these actions.
This new update was rolled out automatically, so there is nothing you need to do aside from checking to make sure your pixel is showing "Microdata" and specifically Schema and Open Graph. To check, you'll need to use your Chrome Pixel Helper. If you don't have the helper, you can easily download it here.
This is a screenshot of my website. As you can see, there are two new events that Facebook now fires on every page, pulling Schema.org and OpenGraph data.
Now, I'm not going to pretend that I even understand what all the code is, but you DO want information in both the Schema and Open Graph. If you do not have microdata, there are plugins that you might need to download in order to get that data. I highly recommend talking to your web developer as this is something neither you (or your Facebook Ad Manager) can do.
Here's the link to the update directly from Facebook.
Here's an easy to understand article on understanding Schema.
Do note, if you use Click Funnels, they have NOT rolled out this update. As soon as I learn that Click Funnels is on board, I'll let you know!