'ello!

The man-page of ln(1) says:

"-f    Unlink any already existing file, permitting the link to occur."


Well, I somehow do not understand the second part of the description.. 
(permitting the link to occur) but - to be honest - I even don't 
understand the first part: "Unlink _any_"? Why any, if I supply an 
argument? (and I think, that I'll always supply ln with an argument)


Thank you & with kind regards,

Petar