There's a mouth inside a mouth. But if you look even closer (not actually, but we're pretending), you can see another mouth inside that mouth... and another one inside of that one! It keeps going and going. Can you count the number of times there's a mouth inside a mouth? This kanji also means revolve too. Think of each "time" a thing happens, it loops back around and comes back to the beginning, revolving around again another time.
If you're having a hard time wrapping your head around the infinite number of times these mouths revolve, just picture yourself in a little kayak (かい) going around and down through the mouths.
Currently there are no similar looking kanji which exist in the WaniKani learning system