A vector is not a magnitude and direction, it's something you can add with other vectors and scale. E.g., the real number line is a vector space, but the vectors have only one component. The scalars are the things you scale the vectors with, they can be either real or complex numbers. This package implements a three dimensional real vector space. All three components are part of the vector, but "x","y" and "z" are scalars, as they prescribe how much unit vector to scale and add to the mix.
The vectors this system implements can be represented as magnitude and direction. For these two concepts you need a little more structure than the addition/scaling a vector space gives you. Once you add a dot product that maps two vectors to a scalar you can measure lengths and angles and think about a magnitude/direction representation. In practice you don't use that for actual computations since it's a nightmarish mess.