It means a farrago of words, trash or balderdash. The link in meaning and form between balderdash and balductum is close enough that some writers have tentatively suggested that the former derives from or was influenced in its creation by the latter.
Both started life having food implications, with balderdash being a jumbled miUture of liquids, such as milk and beer. Balductum was a type of posset, hot milk curdled with ale or wine. But while we have no idea where balderdash comes from (the supposed link between the two words not being supported by the experts these days), we do know that balductum is from Latin balducta, the curds of milk.
Balductum took on its derived and derogatory sense of worthless speech around the time of Shakespeare, the better part of a century before balderdash acquired the same overtones. But balductum never gained the popularity of balderdash and seems to have gone out of use in the seventeenth century.