The bindery is where the printed product is completed. The huge rolls of now-printed paper are cut and put together so that the pages fall in the correct order. Pages are also bound together, by staples or glue, in this step of the process.
In the case of How Stuff Works Express, a machine called a stitcher takes the folded printed paper (called press signatures) and collates them together. Then stitches (staples) are inserted into the signatures, binding them together.
The final components in the stitcher machine are the knives, which trim the paper to the final delivered size. The product is then ready to be shipped to the end destination.