>>84877282okay. let's go right down this rabbit hole and see what happens.
obviously, Barry is a Bee and Vanessa is a human, so regular old penis+vagina=funtimes isn't going to work, but Barry does indeed have the perfect size and physiology to stimulate her clitoris something fierce.
Being fuzzy and having those wings means he can create an incredibly fast vibration while also being fluffy enough to make stimulation softer or harsher by way of pressure against said clitoris, so Vanessa gets a buzz out of it. Moreover, the nectar gun provides another avenue of interaction, allowing Barry to potentially tend to other areas at once.
By extension, Barry also gets to go all the way inside Vanessa all the way up to and possibly beyond her cervix, so he can pretty much take up residence in there and do whatever the fuck he wants to get his little bee dick off. also, by way of toys and such, Vanessa could also find ample ways to provide stimulation for him.
conclusion: they don't fuck in the movie, but you can damn well believe they get freaky in bed.