The phrase "venta de trocas" is a Mexican Spanish phrase that means "trucks for sale" in English. The first two words, "venta de," indicate an item is for sale, while "trocas" is a slang word for "pickup trucks."
The word "troca" is an example of an Anglicism, or the borrowing of an English word. In this case, the Spanish speakers have adapted the English word "truck" into the traditional form of a feminine Spanish noun. Though the word "troca" is common in the United States and Mexico, most Spanish speakers throughout the world do not use it. Instead, they refer to a pickup truck as a "camioneta."