That's saying that programs that exhibit undefined behaviour are not governed by the C++ spec. For a program to be a valid, spec governed piece of C++ code it has to exhibit no undefined behaviour (outside of some constraints). Its accurate to say that any undefined behaviour results in the code being executed no longer being C++, and it can have any behaviour. That's synonymous in common developer speak with 'incorrect', as its desirable for your C++ code to be executed as C++
Honestly, you'd have a better argument by quoting that "Correct execution" can include undefined behavior and erroneous behavior, depending on the data being processed". Which is quite a wild sentence to read, but here we are.