Jajaja Although the meaning of "Carta" in spanish could be "Letter" it also could be "Menu" and the meaning is given by the context of the sentence. It,s like "Lot". - I had a lot of money. - I bought a lot behind the church.
Carta: - El precio del pollo en la carta es de Q 10.00 - Ayer le mande una carta de amor a mi novia. Depending of the context you'll get the meaning.
But beware, because "letter" translates as "carta" only when meaning a written message with several words. "Letter" in the sense of a single symbol within a word (like in 'capital letters', 'four letter word', 'letter B', etc) translates as "letra" :) And it gets more complex since polysemic words have even more meanings.