The tracking technology used by AB and many other websites means that many of the things you do on the web get linked together. For example, if you search for sun loungers on Google and then come to AB you'll probably see ads for sun loumgers appearing. (Only you will see them. Other AB members, viewing the same page, will see different content).
AB is actually run by a company which works in the field of internet advertising (
https://www.silverdisc.co.uk/ ), so you shouldn't be surprised if they're rather good at delivering 'relevant' ads to your screen. (That, of course, assumes that you're not using that-which-shall-not-be-named-here to get rid of the ads anyway!)