Duplicating a product will create a copy of that product and all its sub-products. This is a useful tool when you need to create a new product that is very similar to one that already exists, so that you don't need to start from scratch again.
The duplicated product will have all the same content, settings, and other data copied over. The only differences are that the duplicated product will have "(copy)" in the title, and it (and its sub-products) will be given a unique URL address variation.
Once you've duplicate a product you can then edit it as needed.