Bundling is basically concatenating all small or big javascript and or css files into one huge file to minimize the number of requests and hence load on the server.
To speedup loading of a webpage bundling and minification of the bundled code is necessary. Minification is the process of removing unnecessary characters like whitespace, comments, new line characters etc. from source code to reduce the overall size of the content without changing the functionality of the code.
So, less file size means lesser time to process and download files. Of course, there are various approaches to bundling and minification using bundlers like Webpack, Browserify, RequireJS etc.
Vivishine 