NativeBoost is a library that allows Pharo code to interface with native code written in C/C++. It provides functions for calling external functions, handling basic data types, and working with structures. The tutorial demonstrates how to use NativeBoost to interface with the Chipmunk physics library from within Pharo. It shows defining types for structures like vectors, calling functions, and dealing with indirect function calls through pointers. Understanding native libraries, data types, and structures is necessary to interface Pharo with external C code using NativeBoost.