Coen is a given name and surname.
"Coen" (bold)- is a Germanic variant of the name "Conrad", most popular in the Dutch language. It is originally spelled as "Coenraad" or "Koenraad", with just the "raad" deleted off. Both variations are made up from two words: "koen" (meaning "brave") and "raad" (meaning "advice"). The name translates to "brave advisor".
If someone's official name is "Coenraad", they often use the more casual shorter version in everyday life: thus "Coen" (same for the Koenraad variety).
This is a first name, given to boys, never to girls. Though this is a first (or personal) name, there are people who have it as a surname.
Due to the nature of the Dutch language it is pronounced differently from, for example, English. In Dutch it will sound as one syllable: Koen (like "coon" in "raccoon"), instead of 2 syllables (KOE-en), like "Cohen".
"Cohen" on the other hand, is completely different name with a Hebrew origin meaning "priest". In fact, a "Kohen" is someone who is a direct descendant of Aaron. "Cohen" should not be confused with "Coen".
Read more about Coen: People With This Name, Places With This Name