This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
跇 combines 足 (foot) with 世, but the exact historical development is uncertain. It may have originally related to a foot action, but the precise origin is unclear.
The left side is 足 (foot), and the right side is 世 (world/generation). Picture a foot stepping across generations, but the meaning remains unclear.
For エイ, imagine a foot stepping into an ancient world and hearing an echoing 'A' sound: A -> エイ.