Monsterley_128_bop_200720.zip is a release file of the Minecraft resource pack Monsterley HD Add-On: Biomes O' Plenty, made for Minecraft 1.16-Snapshot, 1.15-Snapshot, 1.16.1, 1.15, 1.16, 1.15.2, 1.15.1. It was published on July 20, 2020 and is 8.6 MB in size. For the full description, screenshots and every other version, visit the Monsterley HD Add-On: Biomes O' Plenty resource pack page.
How to install: Put the .zip into .minecraft/resourcepacks (do not extract it) and enable it under Options → Resource Packs.