This is simply 2d tileset generator. This project only cerate rectangualar shapes world from grass tiles. You can create terrain generator by create instance of prefab GridGeneration (it is available in Prefabs folder). The main/parent gameobiect contains TerrainTileGenerationAssets.cs and TerrainTileGeneratorEidtor.cs script. The last give two buttons. One ("Generate terrain") generate simple rect terrain. Second ("Delete terrain") clear tilemap and generated elements.
The first script (TerrainTileGenerationAssets) contain some public fields which are decide aobut how generated world will look