You ask a diffizil question.
Let us take the example of radio waves. The electrons in the antenna rod get accelerated back and forth and by this they have a common electric field, which oscillates (for a vertically built rod) vertically. The radio wave is polarized by its electric field.
The same result one get if a polarizer foil or simple a narrow enough slit is used. For some range of wavelengths the well designed polarizer foil rotates -from light with equal distributed electric field component (around 360°) - 50% of the light parallel to the slits and let this polarized light through.
Analyzing the behavior of the magnetic field component of the radio wave one observe that if the value of the electric field component points to the up, the North Pole of the magnetic field component develops to the left direction and if the electric field points to the down, the North Pole develops to the right.
But there is a second possibility of the development of the two field components. To illustrate this I placed two sketches of the near field of the antenna radiation:
light has two states of polarization ...
... has to be rephrased to “Photons have two values of the intrinsic spin, right handed and left handed”.