The purpose of N-API is to enable you to use your existing or newly written C/C++ code from JavaScript. This assumes at least a passing familiarity with both JavaScript and C/C++. The level of familiarity necessary is dependent upon the complexity of your project and your involvement with the JavaScript and the C/C++.
For your own projects, it will be necessary to have an understadning of the C/C++ code you plan to integrate as well as what objectives you hope to achieve with your project on the JavaScript side of things.
Many of the tools used to develop N-API modules are run from the command line. So at least a passing familiarity and confidence with your command line tool is essential. IDEs, as described here can help. But they also rely in the command line.