The 5 stands for 5 bolts and the unit for 114.3 is milimeters (mm for short). Sometimes you will also see it as 5x4.5, where 4.5 inches equals 114.3 mm. Be careful, as the mult-fit rims for winters do not generally fit hub centric, i.e. exactly on the hub without a gap. Don't know if it makes much of difference, but I've heard that vibrations can sometimes be an issue. Personally, I would try to get hub centric wheels as this will eliminate any potential problems with balancing.
2011 Kia Forte Ex, Spicy Red