Gives you options for changing character stats (health, regeneration, reach, inventory size, mining speed), add/change/remove armor and vehicle grids, mess with modules, modify recipe costs, change some weapon/ammo values and a few other things.
I've thought about it for a long time, but haven't figured out a good way to do it. As far as I know there's no way to adapt the settings to the mods being loaded in. I could do a "catch all" type thing, but that risks breaking more then it fixes. There is another way that would let the player define what entities to mod, but it requires players to know the internal names, and could make the settings more bloated.
If I can figure out a good enough way to do it I'll add it.