A remainderman usually is someone whose title to property does not become realized until the termination of the ownership of that property by a former owner. Usually this former owner has a life estate in the property and usually has been given that life estate by someone else.
Mimke wills his wife Antje a life estate in his real property and then at her demise title is to pass to his children Johann, Jann, and Metha. Johann, Jann, and Metha are the remaindermen.
Mimke’s will may not use the word “remaindermen,” but it’s possible they are referred to by that term in other legal documents.