Facebook has introduced a new tool for its advertisers that relies on your location and the activities you do on your phone. If you have given the Facebook app permission to track your whereabouts, it will allow selected businesses to target you if you have recently been to one of their shops.
At the same time, your friend – who's sitting at home – can get an advert meant for new customers that you won't see once you've been to that business' store. Since Facebook is giving thousands of businesses across the globe access to people's store visit data, you might encounter the behaviour even while abroad. You might also come across advertisements for companies you've recently interacted with in the real world. Real estate firms could, for instance, show you their latest listings if you called them up.
In the end, it is all up to you as a consumer whether you give permission to the Facebook app to show you more relevant content or not!