It means Indian, indigenous. That's part of an étnia. It is for derogatory use. In Mexico it is used to designate who to belong to the indigenous race in the area of Costa Chica y Montaña (States of Guerrero and Oaxaca).
GUANCO In Mexico : indigenous origins of Costa Chica or Montaña , in the states of Guerrero and Oaxaca. 2 . Derogatory treatment towards a person. .