Facebook allows advertisers to upload lists of their existing contacts to target. This can be some simple combination of name, address, date of birth, gender, etc. It’s not limited to email and phone number. The advertiser may themselves have sourced some of this information from third parties based on other information which they have about you - such as your actual phone number or email address.

https://www.facebook.com/business/help/606443329504150?helpr...