The term Spanish Weight is composed of three words: Arroba (6 letters), PESO (4 letters) and Onza (4 letters). Arroba is a unit of weight and volume used in Spain and Latin America, which is equivalent to 11.5 kilograms or 25.4 pounds. PESO is the name of the currency used in many Spanish-speaking countries, such as Mexico, Chile, Colombia, and Argentina. Onza is a unit of weight used in Spain and Latin America, which is equivalent to 28.75 grams or 1.02 ounces.