Each mask connected to the Use in Unreal node corresponds to a Layer in Unreal. For each mask, you can specify a name and a texture type.
Names: The names are used in Unreal for different items such as the Layer Infos or the Landscape Layer Blend node’s name.
Texture type: You can assign a texture type to each layer. These details will be used by the Landscape Material in Unreal.
There are five types of textures: