Falta (“lack of”) is an interesting word in Spanish because, it is one of those words, along with cornudo that is a grammatical construction that, literally, is less common in the English but rather, in English, the same point is made very commonly in a different way. Falta is very common in Spanish: La casa falta calefacción is literally “the house lacks heating” but the way an English speaker would make that point — since few today say “lacks” in everyday speech! — would be, The house doesn’t have heating.
Falta comes from the Latin Fallita, which means, “a fault.” Indeed, Fault itself comes from the same root — and we can see that with the f-l-t mapping in both. Fallita itself comes from the older Fallere (“to disappoint”) from which we get many English and Spanish words such as fail and fallar.