And maybe they are selling the apples on the side of the road?
I'd say that makes more sense, cos they used 'wij', like the salesman is pointing out that WE specifically, and not other merchants, have apples, so buy from US! :P
In context, if you want to point out specifically that "WE" have the apples then you put the emphasis on (wij). wij is a marked pronoun Therefore when you say "we" using the wij form you would sound higher pitched. WIJ hebben de appels. If you want to say it like "we have the apples" (we hebben de APPELS) then you would have to put emphasis on the noun (meaning you would have a higher pitched voice when saying the noun apples in the sentence.
I know kind of confusing, it took me a while to understand it too.
Well, 'appel' has two plural forms (which mean the same), 'appels' and 'appelen'.
Some plural nouns end with '-s', other with '-en'.