: This stands for High Efficiency Video Coding (also known as H.265). It is the industry-standard video compression format that succeeded H.264 (AVC).
The string 365.Days.2020.1080p.10bit.WEBRip.DDP2.0.x265.HE... is a technical label for an of the film. While the filename reveals detailed encoding parameters (10-bit colour, x265 compression, stereo Dolby Digital Plus), engaging with such files carries legal risk and ethical downsides. 365.Days.2020.1080p.10bit.WEBRip.DDP2.0.x265.HE...