Okay so i started this new job?

i just got hired at this new job and as soon asi staed training and the manager learned that i want bilingual she keeps threating that there going to have to "let me go" if i dont learn spanish. first of all when i went for an intewrview they did not tell me i needed to be bilingual. also, in my application it sas i am not bilingual. my quesion is, is it legal for them to fire me for not being bilingual under these circumstances. the manager keeps telling me there going to have to let me go if i dont learn spanish. is this legal. all day long that is all she tells me "you need to learn, or you can get fired, its required to work here" . but in both interviews i went they didnt tell me anything like that