Selecting "Uncook" or "Export" will attempt to uncook (this is usefull for meshes) or export (again, usefull for meshes) the selected file. Uncooked files will be placed into the /Uncooked folder. Exported files will be placed into the /Raw folder in your mod or dlc project.Different game files will be added to different folders in your mod project depending on the kind of files they are. See here for an explanation of the general modding workflow in Witcher 3.
Exception! Icons (png), certain minimap tiles (jpg) and foliage textures (dds) are not raw files and do not have to be imported to xbm but will be added directly as .png/jpg/dds to the uncooked folder. WolvenKit handles these execptions automatically.