many-fold; multiple layers
Rare, literary word for something folded or layered many times. Often encountered in classical poetry or set phrases.
二十重 is read はたえ and is an old word meaning many layers piled up.
multitude; many layers; crowds of people
Compound of 二十 (はた, 'twenty') and 重 (え, 'fold' or 'layer'). The exact historical derivation is uncertain, but it follows the pattern of other numeral + 重 compounds.