or what it's supposed to contain? Knowing the source would help in determining if it's safe to open.
Use a service like VirusTotal to check the file against dozens of antivirus engines. B1qwer.7z
Usually, files with random or specific shorthand names like "B1qwer" are used for private data transfers, game mods, or software patches. or what it's supposed to contain
Compressed archive created using 7-Zip or similar software. B1qwer.7z