What is Phase Angle and Shifting?

A number of threads make reference to phase angle and time domain. I've seen these terms mentioned before in the context of speaker reviews. In addition, and I don't know if this point touches on the question I just raised, but one of the positive attributes associated with Vandersteen speakers is that the various drivers are time and phase coherent. Because I am not an electrical engineer, I would appeciate it if one or both would kindly provide an explanation of these concepts that a layperson could understand.

On an intuitive basis, it seems that a speaker system with various drivers should be designed in such a way that the crossover does not change the time relationship between the various drivers. Or stated differently, the drivers should work in such a way that electrical signal fed to each driver should reach that driver at the right time so as not to change the overall harmonic structure of the sound emited by the drivers as compared to the harmonic structure of the analogue signal fed into the speaker.

Thanks