On the same note, what happenes to all the olives and other vegetables(olives might technically be a fruit, I dunno) after they make olive oil or other vegetable oils? What about all of the boiled hops when making beer?
It’s used to make animal feeds.
This wouldn’t apply to the bulk of the squeezings, but I believe grappa (a sort of Italian brandy) is made with what’s left from the winemaking process.
My guess would be fertilizer or animal feed.
Oh, and the boiled hops are sometimes composted.
At a winery I visited in Italy (don’t I sound cosmopolitan?), the crushed grapes were composted and later used for fertilizer.
Cher 3 is correct. In France they call the product distilled from the left over glop Pomace; in Italy it’s Grappa, unless it’s flavored with anise —then it’s Sambucca. In Greece, the Sambucca type product is generally known as Ouzo, but also as Tsiporo (Athens and Macedonia), and Raki (Crete).
Grappa is made from the skin of the grapes in Italy. Different grapes gives different types of grappa, and quality varies dramatically (although I can recommend most made by Segnana, and IIRC, the Trentino grape is particularly good).
After the cold pressing of the olives in the frantoio, the paste from the disks that contains the crushed flesh, pits and skins is sent off to processing plants. It is treated with various chemicals to reclaim more oil than can be extracted through normal pressing and centrifuging. The resultant oil is “normal” olive oil, a yellow / straw colour, whereas the oil from cold pressing is green. After all the oil has been removed, the remaining material is used for lots of different purposes, including being used as in ingredient in making bricks, at least in the area where I used to live.
If you ever get the chance to harvest olives and process them in a traditional press (unlikely perhaps, but you never know), just go. One of the best (and longest) days of my life.
BTW, flavoured olive oil is produced by mixing ingredients at the crushing stage - 10kgs lemons per 250kgs olives, don’t know about the others, that was all we did that day.
… and then there is “Vegemite”. Semi-official sandwich spread of Australia made from spent beer wort.
if you’re making wine at home real old-school style, the first thing you do with the fruit is pick it out from between your toes. 
They are now making beauty products with the remaining grape skin in France! Serious! It is suppose to be great for anti-aging creams.