Charlie Zaa takes a Christmas checklist and throws most of it out. The tree, the lights, dinner, presents: "Me puede faltar el árbol" [I can do without the tree], "me pueden faltar regalos" [I can do without presents]. Fine. The one thing he will not go without is you: "Pero tú no me puedes faltar" [but I can't be without you].
That line is worth learning properly. Faltar means to be missing or lacking, and Spanish builds it backwards from English: the thing that is missing is the subject, and the person who misses it is me. So "tú no me puedes faltar" is literally "you can't be missing to me", which is how Spanish says "I can't do without you".
The chorus sets the scene on Nochebuena (Christmas Eve, written here as "noche buena"): "Ya son las 12 y mi puerta suena" [it's already midnight and there's a knock at my door]. He hears the voice, invites them in to dinner, and the song goes soft on one repeated word, Navidad. The second verse strips things down even further, no candles, maybe no music, no glasses, no wine ("Y puede que no haya vino" [and there may be no wine]). It is a sweet, simple idea, sung very earnestly, and it works.