The .part1.rar suffix indicates this is the first segment of a multi-part archive. You will need all parts (e.g., part2, part3) in the same folder to extract the full file.
"HR" can sometimes refer to "High-Res" textures or assets for a video game or 3D modeling software. sc25387-HR.part1.rar
If this is a digital media release, look for a small .nfo file inside. This text file will list the specific technical features (bitrate, codec, source). sc25387-HR.part1.rar