DRM is known as Digital Rights Management by the Gaming Industry, and known as Digital Restrictions Management by everyone else. Any limited amount of installs you have, any mandatory being online to even use your software, anything that breaks your game for not having a certain ID or passing a certain check (in the old days, you needed the manual for these), these are DRM. They arrange it so something is unusable through it if certain parameters aren't met. This is a good place for info on that.

As for UPlay, this is UbiSoft's version of Origin, so to speak. Except without being a mockery to a formerly great company by using said company's name as the client.