If you can share or what software/game it is supposed to be for, I can provide a more detailed breakdown of its specific function.
.rar (Roshal Archive). This is a compressed file format that requires software like WinRAR, 7-Zip, or The Unarchiver to open.
Ensure you downloaded this from a trusted site or a known developer.
Use a service like VirusTotal to check the file for malicious code.