I might be entirely wrong as this is not my expertise at all. From what I learned via the internet is that fields are sort of like volumes of spacetime that permeate everything. Each field has its own excitation of energy. The electromagnetic field is one in which electromagnetism functions in. There are also other fields such as gravitational fields and the higgs field. Each excitation in a field relates to a type of outcome in spacetime. For example, and excitation in the higgs field creates matter. And excitation in the electromagnetic field can create an attractive force, repulsive force, or light. So, the electromagnetic field is the field in which energy’s realizes into electromagnetic forces.