It means that the Adorama web site most likely has some Facebook related code on it, either for a login or a hidden function. When you hit the web site that FB code is invoked and they know you were on the Adorama web site. This is the cancer that FB and their associated services are causing - they can track your access to third-party web sites through the use of frameworks and specific web services that companies like Adorama use to implement their own web sites.
You might want to look at third-party products that can block this type of thing, such as 1Blocker on your Mac, or a router based product like pfBlocker on a pfSense box. These can block most of these types of tracking, and there are other products that can deliver the same results.