That’s a lot of things that happen once the printing process is done! Folding, sorting, binding, finishing and quality check will take place at Post-Press phase. First, it will typically take half a day for the ink to dry. Then, the stacks of printed sheets will get folded by the folding machine. Each sheet will be folded from a flat full sheet that may contain 8-32 pages of a project to a “signature” that the size of it is close to the trim size of the book.
See below example of a full press sheet which includes 16 pages in total on the two sides:
Process of how it is folded to a signature:
Folding process: