Heirs of an estate would like to list real property for sale. All heirs except 1 is in agreement.

If "heirs" means there was no will giving an Executor a power of sale over the real estate, then all owners must sign to list the property for sale, and all must sign the deed to convey the property.   A partition suit can be used to force a sale of the property, normally at public auction, even if one owner disagrees.