"Le raisin noir"
le raisin (singular, masculine in French) translates to grapes.
grain de raisin translates to a grape.
I'm trying to decide if we call them black grapes in Canada. We have green grapes, red grapes, and I think we call the darkest grapes PURPLE grapes. Not that this matters too much in the end.
I have noticed that the only color used so far is this basic lessons is red and black. Maybe the coders of the page are vampires or something lol.
I think it's just the site acknowledging that you haven't been taught that "le raisin" is plural, so it's being lenient.
I am not sure, but I wonder they are referring to the raisin, that kind of dried grape. Black grape I've never seen...
often the dark purple grapes are referred to as black grapes, maybe this helps?