Generic filenames like "File020.rar" are frequently used by to hide the true nature of a file. If you received this file as an email attachment or downloaded it from an untrusted website: Do not open it without scanning it first.
When large files (like software, games, or high-definition videos) are uploaded to the internet, they are often split into smaller "volumes" to make downloading easier. File020 rar
The software assigns generic names based on the order it found them. Generic filenames like "File020