This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development is uncertain. The modern form visually contains 氵 (water) and 午, but the original semantic and phonetic roles are unclear.
With water 氵 beside 午, imagine a noon-time riverbank: the water laps at the shore at midday. This may help recall the kun-reading ほとり (shore) if encountered.
For コ, picture a small child (子, こ) playing by the water's edge: 子 -> コ, and the water 氵 marks the shore.