This is the 4131st most frequent Japanese word.
ヤン
"ヤン" is a casual shortening of "ヤンキー," meaning a delinquent or rebellious youth in Japanese slang.
ヤン is used colloquially here as an ending to imply emphasis, especially in dialectal or casual speech.
ええ、そんなこと分かってるヤン？
Hey, you understand that, right?
ヤン is used here as a proper noun referring to someone's name, Yan.
彼は面白い人だよな、ヤンさん。
He's such an interesting person, Yan.
ヤンキー (Yankee) is a borrowed word used in Japanese as slang to describe a delinquent or rebellious person.