木 is a picture of a tree: the vertical stroke is the trunk, the horizontal is the branches, and the two diagonal strokes are the roots reaching into the earth. A whole tree in four strokes.
木 is both 'tree' and 'wood', and another of the Five Elements (五行). As a radical it appears in hundreds of plant and wooden-object characters: 林 (woods — two trees), 森 (forest — three trees), 树 (tree), 桌 (table), 椅 (chair). Two trees make a grove; three make a forest — Chinese builds big ideas from small pictures.
Trunk, branches, and roots — a whole TREE in four strokes.
Add one more tree: 林 (lín) = woods. Add another: 森 (sēn) = forest. 森林 together means 'forest' — five trees' worth of wilderness.