The Meta pixel is a piece of code on your website that can help you better understand the effectiveness of your advertising and the actions that people take on your site, such as visiting a page or adding an item to their basket. You'll also be able to see when customers took an action after seeing your ad on Facebook and Instagram, which can help you with retargeting. And when you use the Conversions API alongside the pixel, it creates a more reliable connection that helps the delivery system decrease your costs.
On Meta Pixel's Privacy Page you can request and collect all the privacy and GDPR related information that Meta Pixel is providing.