This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
訷 combines 言 (speech) with 申, which likely contributes the sound. The exact historical meaning is uncertain, and the character is rare.
With 言 (words) and 申 (to say/report), 訷 might suggest speaking or reporting, but its meaning is unclear. Picture a mysterious message being delivered.
For シン, imagine a shin (シン) bone being used to tap out a secret message: shin -> シン, and the words 言 are the message.