A lightyear is a unit of measurement used to measure interstellar distance. It is quantified as the distance that light travels in a vacuum over the course of an Earth year.
While it is a measurement of distance, not time, terms for lengths of multiple years can be used to indicate larger values; for example, ten light years could be called a lightdecade, one hundred light years could be called a lightcentury, and so on. Conversely, shorter periods can be used, such as a lightmonths, light days, and so on; Earth's distance from its sun could be expressed as 8 lightminutes.
One light year is the distance that light travels in one Earth year. It is equal to 9.4605284 x 10^{15} meters or 5.878499811103157 x 10^{12} miles. Light years are units of measurement critical to starship navigation.
A light year, also lightyear, abbreviated ly, is the distance light travels in one year.
Since the Galactic Standard Calendar used a year of 368 days, the length of a Galactic Standard Light Year would have been 9,531,961,160,601,600 meters.
This assumes that the the "Galactic Standard" Day, Hour, etc. and Meter are equal to Earth's. The Galactic light year was 0.75% longer than an Earth based light year.
It is also possible that Galactic days (and hours etc.) were 0.75% shorter than there Earth equivalents, and that the light years are the same length. (see below)
The exact length of a light year depends on the exact length used for one “year”. On Earth The IAU uses a Julian year of 365.25 days, while other sources may use a Gregorian year of 365.2425 days, or another year altogether.
Source  year (days)  light year (kilometer)  light year (miles) 

IAU  365.25  9,460,730,472,580,800  5,878,625,373,184 
Gregorian  365.2425  9,460,536,207,068,020  5,878,504,662,190 
365.242199  9.460 528 4 ×10^{15}  5.878 499 81 ×10^{12}  
Yahoo  365.2411^{‡}  9.460 5 ×10^{15}  5,878,482,164,161 
Coruscant  368  9,531,961,160,601,600  5,922,886,070,723 
^{‡} Note that while Yahoo separately reports a year length of 365.24220 days, its rounding of the light year length to five digits, works out to a year length of ~365.2411 days.
