This file appears to be a compressed archive containing for a specific game, likely distributed via Ziperto. Breakdown of the Filename:
: Use a utility like WinRAR or 7-Zip to unpack the .rar file. You will typically find one or more .nsp files inside. MFLD-NSwTcH-NSP-[5DLCPack]-Ziperto.rar
: You will need a modded Nintendo Switch running Custom Firmware (CFW) like Atmosphere. This file appears to be a compressed archive