This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鷰 is a variant form of 燕 (swallow). It combines 廿 (a stylized head shape) with 鳥 (bird), emphasizing the bird nature of the swallow. The exact historical development is uncertain.
The top 廿 looks like a swallow's head with spread wings, and the bottom 鳥 confirms it's a bird. Picture a swallow in flight.
For エン, imagine the swallow's graceful flight ending in a gentle landing: end -> エン, as the bird ends its journey.