.bars is Binary Sound Archive File
Key Features: .BARS File Extension
What is an .BARS file?
A BARS file is a sound archive saved in the Binary Sound Archive format, which is used by various Nintendo Wii U and Switch games. It may store BFSTP or BFWAV sound files that are used for sound effects and voices in the game.
BARS files are developed by Nintendo and delivered with games to package multiple sounds into one archive. Games that use BARS archives include Splatoon and Super Mario Maker.
Since BARS files are packaged with games, you most likely will only encounter the files if you have a dump from the original game. You can extract BARS files using QuickBMS.