Hi Ventakesh,
Check the following post where you can get detailed information about the files:
Component.js and manifest.json
App Overview: The Basic Files of Your App - SAPUI5: UI Development Toolkit for HTML5 - SAP Library
neo-app.json and project.json are the supporting files for thr project.
Example:
project.json:
Languages vary from application to application. If an application supports multiple languages, codes are read from the .project.json file in the order in which they appear.
The build section of the project.json file is updated with the latest settings and the time of the most recent build.
neo-app.json:
This is the application descriptor file you can configure the behavior of your HTML5 application.
The neo-app.json file contains all project settings for SAP Web IDE and is created in the root folder of your project. It is a JSON format file consisting of multiple configuration keys. The most important setting for you to configure is the path where the OpenUI5runtime is located when starting the app.
Create a neo-app.json Project Configuration File
Regards,
Emanuel