Downloading game files (ROMs/NSPs) from third-party sites like ROMSLAB is considered software piracy if you do not own a legal copy of the game.
The .rar extension indicates a compressed folder. Inside, you will find the .nsp file, which is the standard format for Nintendo Switch digital software. SPIRITFARER-NSP-ROMSLAB.rar
Files from unofficial sources carry a risk of malware or "bricks" for modified consoles. Always ensure your antivirus is active and you trust the source before extracting .rar files. you will find the .nsp file