table, flat pieces of wood, slip, leaf
枼 centers on thin, flat wooden objects: a table made of flat boards, a wooden slip for writing, or a leaf as a thin flat piece. The meanings are connected by the idea of a flat, sheet-like piece of wood.
枼 combines 世 (generation, world) and 木 (tree, wood). The exact historical development is uncertain, but it likely originally depicted thin wooden tablets or leaves.
The top 世 looks like a stack of flat sheets, and the bottom 木 is wood. Imagine a pile of thin wooden slips or leaves on a wooden table.
For ヨウ, picture a yellow leaf on a wooden table: yellow -> ヨウ, and the leaf is a thin flat piece like the kanji's meaning.