If the proceeds and cost basis are correct on the 1099-B then you're going to have to explain why the "net to you" is something different.  A logical explanation of that "difference" is that taxes were withheld by the broker but that information would also be on the 1099-B, so it's unclear why you'd ask the question.

I suppose another (remote) possibility is that this is a sale involving employer stock and some stock was sold "for taxes" but the broker combined the stock that you sold "for cash" and the stock sold "for taxes" into one 1099-B, but that seems impossible.