Length of One Year
The length of one year for any planet is the time that it takes it to make one orbit around the Sun. For Earth the length of one year is about 365 Earth days. It takes Mercury only 88 Earth days to orbit the Sun. To see just how swiftly Mercury orbits the Sun compare it to Pluto, which takes over 248 Earth years to make one orbit.
How long is a Mercurian year? In this animation you can watch the Sun rise and set on Mercury over the course of a year. Pay attention to the "STATS" box in the lower left part of the screen. Click on the image above.