What does that mean ? Well, since all C and C++ development floats around different platforms and libraries, you have already seen that the build-process creates an executable for a specific platform. Not only the platform is specific, but also the so-called build settings.
The build settings control many aspects of the compiler and linker process itself, and to be successful, all your components, including any libraries you might use, must have the same settings defined.
See much more on this topic here.