Materials with high coercivity are made into permanent magnets, such as Alnico. The unit of coercivity is ampere/meter.
Materials with low coercivity are made into electromagnets, such as soft iron.
The coercivity can be calculated from the B-H curve of a material. The horizontal distance between points b and a in the BH curve in the right is the coercivity
The unit of coercivity is Ampere/metre