This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development is uncertain. The modern form combines 亻 (person) with 炎 (flame), but the original meaning and component relationship are unclear.
A person 亻 beside flames 炎 might suggest someone calm or at ease near fire, but the meaning is uncertain.
For タン, imagine a person tanning by the flames: tan -> タン, and the person 亻 sits peacefully by the fire 炎.