For an example of this, lets pretend you are leaving Earth on a ship destined for an object, we'll say a black hole, that is 10,000 light-years away. With a futuristic engine, your ship can travel 80 percent of the speed of light. For the point of view of the Earth the trip will take 12,500 years. But according to Special Relativity, by using the above equation, it only takes you on the ship 7,500 years. Although that's still a long time it's quite a difference.
Time dilation makes space travel much more possible.
Another result of the Special Theory of Relativity is that it sets the cosmic speed limit at the speed of light. The above effect of gaining mass at greater speeds is proof of why this is true. The reason is because the faster you go, the more energy you need. At the speed of light your mass would be infinite, and to go faster you would need infinite evergy. Since infinite energy is impossible this prohibites travel at speed greater than the speed of light.