Feliz Navidad is sort of the
Mexican way of saying "Merry Chirstmas". More literally translated, it means "happy Nativity", but close enough.
It is also a fairly cheezy Spanglish Christmas . It was written by Jose Feliciano in 1970, thus making it one of the newest "traditional" Christmas carols. It's words go roughly like this...
Feliz Navidad,
Feliz Navidad,
Feliz Navidad, y Prospero ano y felicidad
I wanna wish you a Merry Christmas,
I wanna wish you a Merry Christmas,
I wanna wish you a Merry Christmas,
from the bottom of my heart.