Typically, files named with the .part2.rar convention are part of a split RAR archive. To successfully extract the contents, you generally need to have (part1, part2, part3, etc.) in the same folder before opening the first volume.
It looks like you're searching for a specific multi-part archive file, likely part of a larger download for . train_sim_world_2.part2.rar
If you are looking for a specific forum post or download link where this file was hosted, could you provide a bit more context? Knowing the or the specific version/mod you are trying to find would help me track down the exact post for you. Typically, files named with the