It facilitated the ability for people to sell (or simply share, I believe you could set $0 prices) meals from their home kitchen to their neighbors. It'd be like putting up a flier saying "We're making a ton of chili, come by 435 Birch tonight if you'd like a bowl!"
Did you look at josephine.com, rather than blog.josephine.com? IMO the former does well at explaining itself. The latter seems to be rather stupid in being a pure social media thing.
Ah, I actually didn't there was another "main" website - I just clicked on "home" in the corner, and that only shows stories about food, not what Josephine does. But now with this and other replies I can see it's a food sharing-like service, thanks :-)