If you are savvy, you have a good practical understanding of something.

如果你有见识，那么你对于某事有现实的了解。

And it's part two of your book that will really help people to develop that practical understanding of how company accounts really work.

这是你的书的第二部分， 它将真正帮助人们对公司账户的实际运作方式产生实际的理解。