.NSP is a standard format for Nintendo Switch digital games.
The file is the second part of a split RAR archive containing the base game files for Monster Hunter Stories 2: Wings of Ruin for the Nintendo Switch. Essential Guide to Extracting Multi-Part Archives MHS2-WOR-NSwTcH-[BASE]-NSP-Ziperto.part2.rar
Do you have all the other (e.g., part1, part3) needed to complete the extraction? MHS2-WOR-NSwTcH-[BASE]-NSP-Ziperto.part2.rar
Because this is a "part2" file, it cannot be opened on its own; it must be combined with "part1" (and any subsequent parts) to access the contents. MHS2-WOR-NSwTcH-[BASE]-NSP-Ziperto.part2.rar
If you previously played the Nintendo Switch Trial Version, you can typically transfer your save data to the full version.