"Ripping DVDs" generally refers to copying the contents of a DVD onto the hard drive, with the intention of compressing the movie using something like DivX. For more information on this, go check out
Doom 9 or
DivX-Digest.
At the request of the movie industry, the world is divided into 6 regions. DVDs produced for one region will not operate in another region. For example, Japan is Region 2 and the US is Region 1. You will not be able to play a Region 2 DVD in a player that is locked for Region 1 and vice versa. Supposedly this is to prevent piracy...more a PITA than anything else, especially if you come from a region that is slow to come up with titles, or has less titles. Generally the US doesn't have the sort of problems other regions have.
Region Free drives get around this limit by not complying with the Region requirements, and play DVDs from all Regions. Unlocked drives are known as RPC1, locked drives (which the majority are, these days) are known as RPC2.