Basically you trade your points in for a discount code that you use at the checkout. There are lots of different discount codes you can get - codes for $$ off, free products, free shipping, the works!  
To do the redemption please log into the website and click on the Rewards Program link in the bottom left corner (on a desktop), or in the main menu on your mobile, then look for the Spend Points button. From there you should be able to follow the points and nab yourself some skin happiness :)