You can use tools like WinRAR or 7-Zip to open the .part05.rar file. Once you open the first part, the software will automatically join the others to reconstruct the original file.
To extract the contents, you must have all parts of the archive (e.g., part01 through the final part) in the same folder.
The "WEB18" portion suggests a web-rip or digital release from 2018.
If you are having trouble extracting it, ensure that no parts are missing or corrupted. Many uploaders provide SFV or MD5 checksums to verify file integrity.