LOD means
Level
Of
Detail ...

LOD 0 is the most accurate and precise Level Of Detail, LOD 1 displays the object seen from a certain distance (decided by the modder), less details can be seen than with LOD 0 etc ...
In most ideal cases an object has more or less 5 LODs, but sometimes only one, the LOD 0, which means that even from far, the game will have to "display" it with details, even if these details can't be seen because of the distance, so more stress on the graphics card and processor ...

According to the object, the LOD value (in meters) will be very different ...
For ex the LOD 0 value for a mesh that depicts a stick doesn't need to be beyond 30 or 50 (meters), it is :
[LOD]
500
... in the Ar-196, which means the stick can be seen with all details up to 500 meters, which is too much ...
... whereas the LOD 0 value for a CF_D0 which depicts a much bigger part of a plane, will still be seen from a bigger distance ...
More here in this tutorial ...
https://www.sas1946.com/main/index.php?topic=357.0Here is an example of a sphere, seen from close (LOD 0 on the left) and from very far (LOD 5 on the right, so less vertices needed, only 140, instead of 5500 ..!)

... and here different LOD aspects for the same object, according to distance, made by Queque ...
