broom
莊 centers on a broom, a tool for sweeping and cleaning. The meaning is a concrete object with no clear abstract extensions.
莊 combines 艹 (grass) with 壯 (strong, robust). The exact historical development is uncertain, but it may relate to a broom made from strong grass or plants.
The top 艹 is grass, and the bottom 壯 suggests strength. Imagine a sturdy broom made of strong grass fibers, sweeping clean.
For ソウ, picture sweeping with a broom and making a soft 'sou' sound as the bristles brush the floor: sou -> ソウ.