This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
儃 combines 亻 (person) with 亶, which likely contributes the sound. The exact historical development is uncertain.
A person 亻 beside the complex 亶 shape. Without a clear meaning, picture a person standing still, perhaps waiting or hesitating, as suggested by one of its kun readings (たたず.む).
For セン, imagine a person (亻) standing still, sending (セン) a silent signal with their posture. The scene of a person sending a message while standing still ties the shape to the reading セン.