"Wij hebben informatie over de verkoop van olie en gas."
Translation:We have information about the sale of oil and gas.
de verkoop is used in situations like "the sale of computers has dropped in the last quarter" (the exchange of a commodity for money), while uitverkoop is a period during which a shop sells goods at reduced prices (e.g. new collection is coming in, they have to get rid of the old stuff) "let's go shopping, it's sale!!!"
verkoop (noun) / Verkopen (verb) is the selling of goods or services. uitverkoop (noun) is when you can get a very good deal, just as the english sale. Par example : De kledingwinkel heeft uitverkoop, meer dan vijftig procent korting!
It seems that olie is used for both 'petroleum' and 'cooking oil'. Is it just the context that determines the meaning?
Yes, that's exactly right. Sometimes you'll also see 'ruwe olie' or 'aardolie'. In all cases it refers to the raw oil as it is harvested, before any processing or refining.