Faster-than-light travel (FTL for short) is used to move from place to place in the universe rapidly, despite the incredible distance between places. Because interstellar travel by conventional means takes a ridiculously long time, science-fiction writers have developed various concepts for faster-than-light travel over the years. Star Trek calls this "warp speed", Star Wars calls it "hyperspace" or "hyperspeed", Macross calls it "space fold", Halo calls it "slip-space" - they all amount to crossing vast distances in near instant time. Without FTL, travel between solar systems would be impossible to survive without going into an extended hibernation.
Games and the larger science-fiction culture have attempted to explain the physics of FTL with varying degrees of success, but generally this is an accepted concept in futuristic settings, and a game will not be criticized too strongly for ignoring the exact mechanics involved. It has also been used to explain, however abstractly, communication over vast distances. Again, gamers tend to accept whatever conventions for travel, communication, or weaponry available in their current universe, so not much attention is paid to those details.
Many games include mechanics like star maps or galaxy maps to visually display to the player just where in space they'll be traveling using FTL. Notable examples of this include Mass Effect, with its interactive 3D map that serves as the main navigational tool during the game's space portions. These maps are necessary to chart a ship's passage through the universe or through conventional space at hyper speeds. As Han Solo once put it, "Without precise calculations, you could fly right through a star or bounce too close to a supernova". Computers to make these calculations are fiendishly complicated and, in games like in Star Wars: Knights of the Old Republic 2 - The Sith Lords, sometimes need repairing before the game's plot may begin proper.
Amusingly, it is technically possible to go faster than the speed of light in Big Rigs: Over the Road Racing, generally accepted as one of the worst games ever made. This isn't even an intentional design on the part of the game's so-called developers; there is no maximum speed limit on the player's truck when it is moving in reverse, so if the player holds down the reverse button long enough, they will technically be going faster than light.