It’s kind of convoluted, but the eventual explanation does make sense, in that travelling at that speed (FTL), you have to be very careful about gravity wells. Most ships tend to give major mass shadows (gravity wells) a wide berth to avoid stress on the ship. The “less than 12 parsecs” just means that Han was able to find a more efficient course along a known hyperspace route by “cutting corners” here and there, thus travelling in a straighter and therefore shorter line. It is related to speed, in that because of the Falcon’s extreme speed, it was able to skirt closer to those gravity wells, since it would be exposed to the stress for a shorter time period. It’s a small bit of fairly “hard” science in an otherwise “Flash Gordon” space opera.
The whole measuring of speed in the Lucas universe, on the other hand, is really bollixed, where something that goes “0.5 past light speed” is faster than ships that go 0.6 or higher. I still haven’t heard a good explanation for that one.
Wow, that's really good. I still like Spock's codes, but your science is neato.
Check out the book “Hyperspace” by Michu Kaiku Hard science for the layman. Facinating read for sci-fi buffs. All his books are really.
Now you know who (one of the guys anyway) Hollywood goes to ;)
MAD Magazine summarized it best: "Our lasers fire at the speed of light but our ships go faster than light... that means we just shot ourselves down!"