Ichi-Dan First Degree in Chinese / Japanese...

In Japanese martial arts, this usually represents the first-degree black belt rank.

It can also be like a linguistic stair step of “more, much more, still more, all the more.” It can also be a step, rung, level, or rank.

Also sometimes used in the context of Buddhism to mean “first step” or “first stage.” This might presume the first step towards enlightenment etc.