The first set of rules looks for elements in a webpage with a matching ID/class name, and removes them. The second set removes URL parameters, which are used all the time for example in referral links, like on Amazon. It looks a bit like &tracking-id="xxxx" at the end of a link. Those rules will remove those as well, providing a clean link without additional tracking that Booking.com uses to identify where you came from, maybe what ad you clicked on, etc etc