There's 3 levels of detail: 0,1,2.
Level 0 - is the most detailed player models, bigger textures, accurate faces, nice-looking grass, etc. This is used mostly in replays, or during the gameplay, when the camera is very close to the player.
Level 1 - player models are less detailed, smaller textures used, faces appear to be generic (although not always). This level is used actively during the gameplay. It looks fine on smaller resolutions, but when you have 1680x1050 or 1920x1200, the artifacts become visible.
Level 2 - the models are much simpler, the polygon count is lot smaller. Small textures used. It looks ok, when the object is far from the camera, but not when it's close.

As the players move to or away from the camera (viewer), the game engine decides which LOD level to use, because it tries to maintain a good constant framerate, and there's no point using Level 0 for a player, which only occupies 10x20 pixels on the screen.

So, when you adjust the sliders in LOD Mixer, you change those switch-points, when the engine decides to go from one LOD level to another. For example, if you move both of them all the way to the left - then Level 2 will be always used. It won't be pretty, but it'll be much less work for the graphics card. On the other extreme, if you move both sliders all the way to the right, then Level 0 will be always used. It won't look perfect either (unless you have a really large screen and a really good videocard), because there will be aliasing, and the frame rate will drop, so the gameplay will become really choppy. The right solution is somewhere in the middle, but you'll need to find it by experiment, as it will be slightly different for everyone, depending on exact specs of your PC. Default slider position are 0.095 and 0.070. (If you uncheck the "Custom LOD configuration" checkbox, the sliders will return to their defaults)

Dzięki za rzucenie odrobiny światła na to narzędzie
Dalej jednak nie wiem po co są 2 suwaki z technicznego punktu widzenia.

Pierwszy suwak zmienia usatawienia high-medium natomiast drugi odpowiada za medium-low

Pierwszy suwak zmienia usatawienia high-medium natomiast drugi odpowiada za medium-low

Chyba coś tu nie tak mówisz, kolego
Jeden suwak odpowiada za wygładzanie krawędzi, drugi natomiast za detale, tylko nie wiem który jest który, juz zapomnialem, ale nie możemy dać maksymalnego wygladzania krawedzi, jesli mamy detale na najniższe, mozemy zrobic odwrotnie, mozemy miec detale najwyzsze a najmniejsze wygladzanie krawedzi.