The Spanish expression "empresas de pintura" translates into English as "paint companies." Generally this is in reference to a company that provides painting services rather than a company that sells paint.
The word "empresas" is the plural form of the noun empresa, which translates into English as company. The word "de" is a preposition meaning from or of in English. In this expression "de" serves to indicate a characteristic of the company. "Pintura" translates as either painting, such as the Mona Lisa, or as paint, such as the substance used to make the Mona Lisa. In the context of the expression, "empresas de pintura," the word carries the latter meaning.