Is there any working Natural Language Generation (NLG) system which can describe the numerical data in a financial balance sheet. If so, please provide the code/resource. I tried but couldn't find any working system.
There is nothing as far as I am aware which automatically takes a spreadsheet and just describes it, without a developer having to define the process by which the data is processed to natural language. Natural Language is incredibly complex.
The NLG Wikipedia article gives an overview of a common process for converting data to text. There is also a recent survey paper.
Your question in its current form is too vague to provide anything more than links to such resources. It is more of a question of "How do I convert my data to natural language" than "How do I convert data to natural language". It is a highly domain-specific task.