Typically, web page visitors are tracked by ad trackers. Apple is turning the tables on Safari by showing Safari users which ad trackers are active and blocking them when necessary. Firefox and Brave already offer such a function.
The new privacy feature for Safari is located in the upper part of the browser, right next to the address bar. There may well be 200 ad trackers there. Users can open the anti-tracker function and get a detailed privacy report.
Most trackers are used for advertisements, as they allow you to target the ads to the user. In this way the ads match the interests of the visitor. With such an ad blocker this is of course no longer possible.
The new Safari functions including the ad tracker will be included in the upcoming operating version MacOS Big Sur. This is scheduled for release in autumn 2020.