Every show is filed under one category. Buyers see it as the small line above the show's title, and you can filter the shows list by it.
Built-in categories
Only one comes with the box office: Uncategorized. It is where a new show starts, and where a show lands when its category is deleted, so it cannot be removed. While you leave its name as it is, each language shows it in its own words; rename it and your name is shown exactly as you typed it. Its slug stays. Everything else (Stand-up, Theatre, Workshop, whatever your venue sells) you add yourself. Buyers do not see «Uncategorized» on the show page.
Add or change a category
Click Add category. Give it a name; the slug is made from the name (letters, digits and hyphens, in any language) and you can change it. Order decides where it sits in lists and in the show form: lower numbers come first, and a category with no order goes last.
Use the edit icon to change a category's name or order, or the slug of one you added.
Remove a category
The trash icon deletes a category you added. The shows filed under it (those in the Trash too) are not deleted: they move to Uncategorized, and the confirmation tells you how many. You can give them another category later on each show's Details tab.