It means a digital scan of the actual film negative.
Usually when they use this phrasing They mean to delineate a scan from the original film negative, as opposed to an interpositive.
Example- Scream Factory did a 2K scan of an interpositive for their release of The THING.
Arrow's release of The THING has done a 4K scan of the original film negative.
(Of course, that wording ('original film elements') is vague enough that it could mean either. But I have always taken it to mean the original negative)