Where does he learn this stuff?

Last night Nate was playing in the floor with some "balls". Really was gum balls but he didn't know that. He was counting them and putting them in a little cup. Next thing I know he says "uno, dos, tres, quatro"! I seriously do not know where he learned this! A few times I have said spanish to him (which makes me chuckle because my spanish is horrible) but he would never say it. He is amazing :)