This indicates that the original data was too large for a single file and has been split into multiple pieces (e.g., part1, part2, part3). You cannot extract the contents using only "part1"; you must have all sequential parts in the same folder to successfully open them.
Always scan compressed files from unknown sources with updated antivirus software before extracting, as archives are a common vector for distributing malware. MrsL_lng.part1.rar
Many files with this naming convention are password-protected by the original uploader. You will likely need to refer back to the source where you found the link to find the decryption key. This indicates that the original data was too