Readings & Meanings:
to rule, govern
I treated my cavities.
She knows a lot about politics.
I dislocated my shoulder, so I want that fixed.
The public peace in New York has improved a lot, compared to previously.
Our old friend 水 is here in the San-sui on the left.
台 is normally, now, a counter for vehicles. Here, think of it as a pictograph showing heavy pressure (from above) on the ground.
Add 水 to pressure and you get "controlling the flow of rivers." This can feed into the meaning of "calm, settle down" as well as "to govern." Plus, if you are controlling a river that often overflows, you are "fixing" the problem, "healing" the cities damaged by flood.