Basically, it is a browser function to print a page. You have some possibilities in your CSS (media="print") to have a better print layout.
For single modules you can use a skin object (PRINTMODULE) to print the content of that module, see Create a Container -- DNN Docs (dnncommunity.org). This opens a window that displays the content of the module, than you can print it with your browser's pront function. Afair you can also have a special css file to get a specific layout (or maybe a skin file, I don't remember exactly, I never used that...).