You cannot open or play Part 3 on its own. If you are missing Part 1 or Part 2, the extraction process will fail.
Always scan .rar files with updated antivirus software, such as Malwarebytes, before extracting, as archives from third-party sources can occasionally contain unwanted scripts or malware. D0sS0nMlt1tud.m720p.yamil.part3.rar
This is likely an obfuscated or encoded title of a film or television show. "D0sS0n" often replaces letters with numbers (Leet Speak), suggesting the word "Dos Son" or "Dissonance." "Mlt1tud" likely translates to "Multitud" (Spanish for "Multitude"). You cannot open or play Part 3 on its own