It's a randomly created name for a directory to store windows update files.
Microsoft uses "GUIDs" as directory names for some updates, to ensure they do not conflict with any other possible name.
GUIDs, Globally Unique Identifiers, are random numbers so massive that there is effectively zero chance of any two being the same.
(Another standard is "UUID" - Universally Unique Identifier).
https://en.wikipedia.org/wiki/Globally_unique_identifier