I give a lecture to people about growing grapes and making wine. It's basically grapes and the juice. You have to do analysis, determine whether or not additions of acid or sugar need to be made, decide what kind of yeast to use. It can be as little as three months and as long as two years. Actual fermentation takes less than 15 days.
Yeasts eat sugar, they burp carbon dioxide and they pee alcohol.
Organizing work for the cellar crew, ordering supplies, talking to salespeople, reporters, people at the resort, working with the wine market upstairs, the distributor, the public. Winemaking is some chemistry. It's a lot of judicious choices about what to do, when to harvest, what to do with the wine, how to age it, how to handle juggling all the different tanks, blending, a lot of processing that goes on. You have to do it in a timely fashion. You've got to be skilled in everything from chemistry, physics, biology, business, marketing.