user_mapping_options contains all the options defined for user mappings in the current database. Only those user mappings are shown where the current user has access to the corresponding foreign server (by way of being the owner or having some privilege).
Name of the user being mapped, or
Name of the database that the foreign server used by this mapping is defined in (always the current database)
Name of the foreign server used by this mapping
Name of an option
Value of the option. This column will show as null unless the current user is the user being mapped, or the mapping is for