"He sells vegetables in this store."
Translation:Il vend des légumes dans ce magasin.
This might be very subtle, but why not "les légumes" here? In English, "he sells vegetables" implies that he sells vegetables in general. Not just a certain set of vegetables -- the statement is "he sells vegetables." Wouldn't it be correct to say "Il aime les légumes" if you wanted to say that "he likes vegetables?" I don't see the difference.
For direct objects of verbs of preference, use "les". J'aime les légumes. I like vegetables. Otherwise, use "des". Je mange des légumes. I eat vegetables.
If you're talking about SPECIFIC vegetables, you would use Les. If you're just saying vegetables in general, or non-specific vegetables, you use Des.
Because a boutique is usually a small store that sells specialty items, magasin would be something like a grocery store (épicerie) or a large scale music store
In French, the term "boutique" is not so specialized. It may be any kind of "shop".