The phrase "ventas de buses usados" means "sales of used buses" in English. The word "venta" in Spanish is related to the word "vend" in English and means "sale." Here it is used in the plural to mean "sales."
The phrase "ventas de buses usados" can be used to search for used buses for sale, or to advertise the sale of used buses. A search of "ventas de buses usados" primarily yields results advertising the sale of used buses in a variety of locations. To narrow such a search, add the name of a region, city or state to your search.