Llenar comes from the Latin plere (“to fill”), as we’ve previously discussed. But here’s another English word that comes from the same Latin root: expletive, yes, that euphemism for vulgar words!
Expletive literally means to “fill” with the expansive ex– prefix which, taken together, mean, “to fill out your words.” An expletive is literally filling conversation with words when you don’t know what else to say!