The file extension .R02 is that given to the 2nd part of a WINRAR split compressed archive.

A WINRAR split compressed archive is a compressed archive split into several parts. The benefit of this being that by splitting a single archive into numerous parts, you can store the archive in chunks across multiple disks.

With each section of the split archive being given a corresponding extension i.e. r01, r02, r03, and so on.

WINRAR is 'archive management' software, allowing you to backup and compress data, reducing file size, which is beneficial for data storage or for data transfer over the internet, etc.

WINRAR also allows users to decompress or unzip data files downloaded from the internet.