Complex sentence: In C and C++, it is a type qualifier, like const, and is a property of the "type;" further, it does "not" work in most threading usage, and this use is discouraged.
Split into simpler sentences: In C and C++, it is a type qualifier, like const, and is a property of the "type". Furthermore, in C and C++ it does "not" work in most threading scenarios, and that use is discouraged.