they just slow down... hyperspace in the star wars enviroment is just faster then light, exactly what Einstein (sp?) mathematically calculated was to be impossible.
"She'll make .5 past lightspeed"
so basically hes saying that the falcon can go "one and a half" of what lightspeed is. Which, say you were travelling to alpha centari, would take (completly random guess) about 1000 times longer travelling at the speed of light then to travel through a wormhole, which I am guessing is simply what happens with a blackholes, where space is actually warped into a particle smaller then an electron, is forced into into the black hole, and everything else follows this new curve of space, which then reappears in another black hole.