Hyperspace was an alternate dimension that could only be reached by traveling at or faster than the speed of light. Hyperdrives enabled spacecrafts to travel through hyperspace lanes across great distances, enabling travel and exploration at unprecedented rates.
Hyperdrives manipulate hypermatter particles in order to thrust a starship into hyperspace by taking advantage of the wrinkles in the fabric of realspace, whilst still preserving the ship's mass/energy profile. This shortens journeying distance significantly, allowing the vessel to jump from a specific point to another point without having to travel directly between them, therefore reducing journey time by an extraordinarily large margin.
However, large objects in realspace cast "mass shadows" in hyperspace, so hyperspace jumps necessitate very precise calculations. Without those, a vessel could fly right through a star or another celestial body. Because of the danger, hyperlanes are all but required to fly through hyperspace.