Pffff,
A light year is 3 individual constants
distance
speed
time
No.
A distance is something you can measure with a yardstick or a meter stick. Typical distances are in meters, miles, centimeters, kilometers, inches, etc. But, for example, 2.54 centimeters is the same as an inch and 1000 meters is the same as a kilometer.
A time is something you measure with a clock. Typical times are seconds, minutes, hours, days, weeks, years. But, for example, a day is 86400 seconds and a week is 7 days.
An event is a point in spacetime. It has a location (usually given by three distances (x,y,z coordinates) and a time t).
A (Lorentz) frame is a specific choice of space and time coordinates so that points with fixed spatial coordinate do not move with respect to each other (they maintain the same distance apart over time).
Two different Lorentz frame will move with respect to each other and can measure different distances and time intervals between events.
Something in motion will move a distance in an interval of time. The speed of the object is then the distance divided by the time. So, typical speeds are meters per second (m/s), miles per hour (mph), kilometers per second (km/s), kilometers per hour (kph)., or inches per week. But, for example, 3600 kilometers per hour is the same speed as 1 kilometer per second, 1 mile per hour is the same as 1.609 kilometers per hour, and .447 meters per second.
So, in general, speed=distance/time. It is measured as a distance per time.
An old joke: A guy gets pulled over by a cop. The cop ask him if he was aware that he was driving at 100 miles per hour. The guy says, "That's impossible! I've only been driving 10 minutes!".
Now, if I am going at 100 miles per hour (a speed) and go for 2 hours (a time), I will go 200 miles (a distance). So, in general, a speed times a time is a distance.
Now, the remarkable thing about light is that it has the same speed in all frames of reference. This speed is 299,792,458 meters per second (m/s).
So, if light travels for 3 seconds (a time), it will go 3*299,792,458=899,377,374 meters (a distance). We can also say that this *distance* is 3 light seconds. It is the distance light travels in 3 seconds.
In the same way, light, going at the speed of light (a speed) for one year (a time) will go about 9.5 quadrillion meters (a distance). This distance is also known as a light year.
So, a light year *is* a distance. In particular, it is the distance that anything moving at the speed of light will travel over the time interval of a year.