Refers to someone who talks a lot, often in a trivial manner.
Ese charrulo no para de hablar, siempre tiene algo que contar.
That chatterbox doesn't stop talking; she always has something to share.
Siempre que voy a la fiesta, el charrulo no deja de hablar de sus aventuras.
Whenever I go to the party, the chatterbox doesn't stop talking about his adventures.