Based on the naming convention, this .rar file probably contains:
: This file is designed for modified Nintendo Switch consoles or PC-based Switch emulators . Safety and Usage Notes MASTER-BLASTER-1_2-NSP-ROMSLAB.rar
: Downloading ROMs or NSP files for games you do not own is a violation of copyright law. Furthermore, using NSP files on an online-connected Switch carries a high risk of a permanent console ban from Nintendo services. Based on the naming convention, this
: This is the "scene" tag or the name of the website/group that uploaded or curated the file. What is likely inside? Based on the naming convention