Check this Facebook Newsroom post for more details; the tool is initially rolling out in Ireland, South Korea, and Spain
"The company introduced a new tool that lets people better see and control the information that Facebook has gathered about their browsing habits outside the social network.Facebook’s New Tool Lets You See Which Apps and Websites Tracked You | NYT
The tool, Off-Facebook Activity, allows users to view the hundreds of sites and apps that share data and customer information with Facebook. They can disconnect the data from their account if they want.
“This is another way to give people more transparency and control on Facebook,” the company said in a blog post. It added that people generally had more than 80 apps on their phones and used about half of them every month, making it difficult to know which ones had collected personal information and how the data was being used."