Klaas, I think the more important thing to know is why Kevin Bacon! If you aren't an American or GenX or younger (or maybe both), it might be a cultural reference that flies right over one's head.
"Six Degrees of Kevin Bacon" is a game to find the connection between any actor or actress and Kevin Bacon in six steps. Other versions might be to find the connection between Kevin Bacon and anyone, not just actors.
It took it's name and number from the play and film that came out in the early 1990s, Six Degrees of Separation, which suggested that we are all connected within six degrees.
In Six Degrees, acquaintances count, unlike WikiTree's connection where there needs to be some kind of familial tie. But the basic idea is the same.