Update181 indicates this is update version 1.8.1 for the game.
The file is a compressed archive containing a software update for a Nintendo Switch game. Based on the naming conventions used by the source site Ziperto , File Identity Report KT-NBE-NSwTcH-NSP-Update181-Ziperto.rar
NSP stands for Nintendo Submission Package , which is the standard file format used for games and updates on the Switch console. Update181 indicates this is update version 1