Only open the file if you trust where it came from. Avoid downloading software from unofficial sites like "7zip.com" (the official site is 7-zip.org ), as they may distribute infected installers.
You may be able to right-click the file and select Extract All directly in File Explorer. Using 7-Zip (Recommended): isfull.7z
Like a ZIP file, it bundles multiple files into one smaller "package" to save space or make them easier to send. Only open the file if you trust where it came from