Why are unpaired electrons more significant than paired electrons in terms of magnetic properties

Opposite spin neutralizes the magnetic fields.

Explanation:

The reason for the significance of the unpaired electrons with respect to the magnetic properties is because electrons have opposite spin and when the electrons are paired then as a result their opposite spins neutralizes the effect of their magnetic field thus resulting in no field effect.

Thus single electrons which are unpaired contributes to the magnetic properties of the material as compared to the paired electrons.