This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 屛 is uncertain. It appears to be a variant of 屏, which combines 尸 (a roof or shelter) with 并 (possibly phonetic and meaning 'to combine' or 'side by side'), suggesting a screen or partition.
The outer 尸 looks like a folding screen, and the inner 幷 resembles panels joined together. Picture a room divider made of connected panels.
For ヘイ, imagine a folding screen shaped like the letter H, and you say 'Hey!' when you see it: Hey -> ヘイ.