Since this is "part7.rar," you cannot extract it in isolation. You must have all preceding and subsequent parts (e.g., part1 through partX) in the same folder.
This filename appears to be a specific segment of a multi-part archive (Part 7). Because the naming convention is highly specific and likely related to a private or obscure dataset, a general guide for managing and extracting such files is provided below. 1. Extracting Multi-Part RAR Archives sc25287-WLFDDE.part7.rar
: Before opening the extracted contents, run a scan using VirusTotal or your local antivirus, as obscurely named RAR files are often used to distribute unwanted software. Do you have the other parts of this archive, or Since this is "part7