Okay kiddo, imagine you have a giant bathtub filled with grape juice. That's what people use to make wine. So if there are too many grapes and not enough people drinking wine, the grape juice just sits there in the bathtub, waiting for someone to turn it into wine. This is called a "wine lake," and it's a problem for people who make wine.
It's like having too many toys but only one kid to play with them. The toys just sit there, taking up space and nobody is happy. In the same way, the grape juice just sits there, taking up space, and nobody is happy if there is no one to drink it.
To fix the problem of the wine lake, people can do things like make less grape juice or find new markets for their wine to sell more of it. It's important to use the grapes in the bathtub so they don't go bad, and everyone can enjoy a nice glass of wine in moderation.