fields divided by dikes
畾 centers on a landscape of fields divided by raised boundaries: a pattern of rice paddies or farmland separated by dikes.
畾 is formed by tripling the 田 (field) component, visually representing many fields divided by dikes. The exact historical development is uncertain, but the reduplication pattern is a common way to express plurality or intensity.
Three 田 (fields) stacked together show a patchwork of farmland separated by dikes. Imagine looking down on a valley of rice paddies, each bordered by raised earth.
For ルイ, picture a ruler (ルイ) measuring the dikes between the fields: ruler -> ルイ, and the ruler helps divide the land.