米 (mǐ) — (classifier) meter (unit of length)

Here 米 is a measure word for length: 一米 = one meter. Don't confuse with 米饭 (cooked rice) or 大米 (uncooked rice grains).

A drawing of the thing itself, worn down over three thousand years into a few strokes.

米 is a picture of rice kernels without husk, with the horizontal stroke as a bamboo sieve. It is unrelated to similar-looking grain characters.