The FB API is not like VK.
Facebook has different id for all types of entries, so to access any functionality you need to know the id of the entry and the name of the desired API function. In a particular case, you are interested in the /likes method.
An example of getting a list of those who liked:
GET https://graph.facebook.com/v2.5/{id того, кто запостил}_{здесь_указываем_id_записи}/likes
An example of getting a list of those who liked the number of likes from the post on my page (this is a real example, only without access_token):
https://graph.facebook.com/v2.5/963586523696776_963070623748366/likes?summary=true
The answer is:
{ "data": [ { "id": "963586523696776" } ], "paging": { "cursors": { "after": "OTYzNTg2NTIzNjk2Nzc2", "before": "OTYzNTg2NTIzNjk2Nzc2" } }, "summary": { "total_count": 1, "can_like": true, "has_liked": true } }
summary=true is responsible for counting the number of likes. If you do not specify it, then fb will simply send a list of people who liked the entry.