The name Koen is a boy's name meaning "bold advisor". Koen and is often added to lists like Kool K Baby Names and discussed in our forums with posts like "CAF, Searched lists".
From the experts:
A short form popular in the Netherlands, though in the U.S. Koen and Coen are easily confused with Cohen, the Jewish surname meaning "priest" which has recently gained currency as a first name. The Dutch pronunciation is more like "coon."