From Spanish, the phrase "venta de borregos" translates to "sheep for sale" in English. "Venta" means "sale", "de" means "of", and "borregos" means sheep, or possibly lamb.
Note there is possible ambiguity in this phrase. Borregos may mean sheep (referring to the adult animal) or lamb (the baby animal). It also may refer to live animals requiring pasture, or sheep or lamb meat (aka mutton) for consumption. It may be necessary to contact the seller for more information as to whether the sheep are being sold as meat or livestock, as well as the age of the animals in question.