It's the name of a city in California, and it was given this name by the Spanish explorer Gaspar de Portolà in 1769.
The name is derived from the Spanish "Nuestra Señora la Reina de los Ángeles de Porciúncula" which means "Our Lady Queen of the Angels of Porciúncula". It refers to a Catholic order, the Order of Friars Minor, who had a chapel dedicated to the Virgin Mary.