This is almost certainly the catalog or serial number. In many production libraries (especially East Asian media archives), this unique string allows you to cross-reference the exact title, release date, and studio information on dedicated databases. Think of it as the ISBN for video content.
This filename tells a complete story: A cataloged release (SONE-360) featuring a specific artist (Saika Kawakita), dated mid-2019, flagged for adult content, presented in Full HD, and compressed using next-gen AV1 codec. SONE-360.Saika.Kawakita.19.09.24.xxx.1080p.av1....
Software and Apps: