A function prototype is a definition the which is structured in the same way as a normal function is structured, but in instead of containing code, prototype ends in a semicolon. Function prototypes is a C or C++ concept and not relevant to Java.
In c++ we have a concept of function signature which consists of the function prototype. It tells you is the general information about a function, its name, parameters, what scope it is in, and other miscellaneous information.
static const int & MyClass::MyFunc(int a, int b);
In Java we have a concept of method signature which consists only of the name of the method and the parameter types and their order.