name of a Chinese emperor
禹 is a rare kanji that refers specifically to the name of a legendary Chinese emperor. It has no clear standalone meaning beyond this historical name.
The origin of 禹 is uncertain. It is an ancient character used as a proper name, and its component breakdown is not clearly established.
Think of 禹 as a pictogram of a legendary figure, with the top stroke suggesting a crown and the lower part a stylized body. Remember it as the emperor's name.
For ウ, imagine the emperor's name echoing through a long hallway: 'Uuu' — the sound cues ウ.