admonish, dissuade
諌 centers on using words to steer someone away from a wrong course: admonishing or dissuading them from an action.
諌 combines 言 (speech) with 東, which likely contributes a phonetic element. The character is a variant or simplified form related to 諫, which uses 柬 as the phonetic. The exact historical development is uncertain.
The left side 言 is speech, and the right side 東 looks like a bundle tied with a cord. Picture words wrapping around someone like a cord, pulling them back from a bad decision.
For カン, imagine a can of advice: you open the can and out come words that admonish and dissuade. Can -> カン, and the speech radical 言 delivers the warning.