What is the fruit of a palm tree called?

The most likely palm you are referring to is Butia capitata, or the pindo palm, also known as the jelly palm. It is usually short and stocky with yellow roundish fruit. Do not confuse it with the Queen Palm which is far taller and skinnier and has oval-shaped orangish fruit when ripe. The fruit of the Butia is edible, the fruit of the Queen palm is not. There is a video on the internet about this palm, type in eattheweeds episode 31