Samsung is normally press-to-connect, no PIN needed (or supplied).
Belodion, WPS is Wi-Fi Protected Setup - you press the WPS button on the router, press the WPS button on the phone, and they negotiate passwords. It's actually easier than typing in a password if you can reach the router's button from where you're sitting. (If you have to get up and cross the room, it's probably easier to type in the password.)