At the speed of light, it takes you a year to travel a light year. In its own frame of reference, time seems to have stopped. Of course, to travel at the speed of light you need to have zero mass. The time it takes us to travel a light year is (as expected) considerably longer than a year.
If you're wondering, there are about 31,500,000 seconds in a year, and if you multiply that by 186,000 (the distance light travels every second), you get 5.9 trillion miles (9.4 trillion km) the distance light travels in a year. The first discussions about the speed of light began with the Greek philosopher Aristotle, who considered that light traveled instantaneously. A trip that lasts a light year or a billion light years for a person traveling at the speed of light will seem absolutely the same over time. On spaceships, time would pass differently, so one wouldn't even have the feeling of traveling and travel time would fly by in less than a second.
If the spacecraft were traveling at the speed at which Helios 2 was traveling, it would have traveled one light-year in 4269 light-years. The spacecraft was carrying two astronauts traveling at an average speed of 28,163 kilometers per hour. Numerous experiments have shown that, in fact, time flows differently when it travels at the speed of light. However, for a man traveling in a spaceship at the speed of light, time would not flow the same as outside the spaceship.
The speed at which it will fly depends on the orbital altitude, which is approximately between 304 kilometers and 528 kilometers above sea level, depending on the mission. If a spaceship were to travel at the speed of one light-year, it would cover the distance of one light-year in a human year.