Use apps like RAR (by RARLAB) or Documents by Readdle to open these on your mobile device.

If you get an error while opening, try the "Repair archive" feature in WinRAR. This works best if the creator included a "recovery record" when making the file. 💡 Why People Use RAR instead of ZIP

RAR usually creates smaller files than ZIP, saving you disk space and making uploads faster.

If you can tell me where you found (like a specific game mod site or a work project), I can give you more targeted help! How To Open, Create, and Convert RAR Files - AVG AntiVirus