Reason for rejection: Guideline 2.1 - Performance > App Completeness

Your app or its metadata does not appear to include complete and final content. Specifically, your app description and promotional text is insufficient and lacks detail regarding the app’s features and capabilities.

App Store users expect the apps they download to be ready for public use. Apps on the store shouldn't include placeholder or incomplete content or information.

What does it mean?

How to resolve it? 

Revise your app and metadata so that all of its content is complete and final.

• Your app binary or metadata should not include "lorem ipsum" text.
• App metadata should not include placeholder screenshots, such as "screenshot coming soon".

Moreover, ensure that your app description has sufficient information/details on your app's features and functionalities.

Do I need to generate a new build?

No.