This is the 1173rd most frequent Portuguese word.
carta
"Carta" in English means "letter" (written communication) or "card" (such as playing card or greetings card).
In this sentence, 'carta' refers to the written communication as a physical letter.
Eu escrevi uma carta para meu amigo ontem.
I wrote a letter to my friend yesterday.
Here, 'carta' refers to a playing card used in card games.
O jogador jogou sua última carta para vencer o jogo.
The player played his last card to win the game.
In this usage, 'carta' signifies a chart or map meant for navigation purposes.