You may prefer to say Jin is a kind of fairies (or you may refer that as elf, depending on how you describe it in Chinese).
The full name of Jin should be Jinni (精靈) which is the type of mysterious creature you saw in or heard from the book "The Magic Lamp" (阿拉丁神燈).
Jinni is a word originated from the Islambic world (伊斯蘭世界), usually refers as "a spirit capable of assuming human or animal form and exercising supernatural influence over people".
You can pronounce the word as Jin in "Jingle Bell" or as [j -in] with "j" as the "j" sound in "jet" and "in" as the word "in"
參考: Some fanatic research articles and dictionaries + my own research in myths and legends