Once I was told that I am the second cousin of my uncle's son?
Where the number before cousin doesn't depict the number of cousins, but rather it tells how close of a relation you are in with the person.
But how does this works out? What would be my real brother be to me if the relation is evaluated using the above method. And how many cousins could exist like that? can there be fourth/fifth...eighth cousin also?
Firstly you are miss-informed
Your Uncles son is your cousin (1ST cousin) not your second cousin (Unless he is not a real uncle).
Secondly only cousins are referred to like this not Brothers.
Thirdly The relationship is easy to relate
Your cousins offspring (children) are your Second Cousins.
Your Second cousins offspring are your third cousins etc.
Usually after Third cousins we drop the count and refer to them as distant relatives.
I believe Americans have some term related to Kissing cousins, which has some type of connection to this, But I am English