To learn more there will be links to great videos and Stanford's Folding@Home site so you the user get the best information possible.
Stanford F@H website: http://folding.stanford.edu/
Great Video by Pande Lab Science: https://www.youtube.com/watch?v=7sJx9z1uB9k
This is not directly on what F@H is but the hardware used (NOTE: Video and hardware from 2015) LinusTechTips: https://www.youtube.com/watch?v=MfG9ZSnJdR4
The long and short of it is that your unused computer power will be used to simulate protein folding and help not only those affected now but those who will be affected which could be you, your mother, your sister, your boss, your teacher, or your long lost friend from high school. Every little bit helps and if your PC is not up to spec then you can always donate on our donate page to help us build more servers and computers to help compute the protein simulation.