Details about sandbox tool, skatter plugin and laubwerk plugin are given below :-
Sandbox Tools - The Sandbox Tools (help.sketchup.com) extension employs the concept of a sandbox that belongs to a surface to be formed and manipulated with sandbox tools. A sandbox in SketchUp (and in other 3D modeling tools) is generally defined as a triangulated irregular network or TIN in terrain Modeling terminology. The sandbox tool is used to model terrain and design landscape.
Skatter Plugin – This plugin (getskatter.com) can be used to render huge amounts of vegetation, instantly populate city blocks, generate parametric assemblies, crowds, carpets etc. all right inside SketchUp.
Laubwerk – This sketchup plugin (extensions.sketchup.com) can make your models realistic with superior quality vegetation. It allows the users of V-Ray or Thea for SketchUp getting access to a wide-ranging library of render-ready, realistic, procedural 3D plants.
To learn the complete process for modeling & rendering a villa, go through the following video tutorial.
Video Source: KG Studio