I assume that is meant to say "expecting a name, but did not find one". A "name" is a specific type in a PDF file. Names are used in key value pairs, so that the PDF processor can find certain information (e.g. it's looking for an item named "MediaBox" to determine the page size for a certain PDF page). I assume that because of a problem with the software that created the PDF file, something that is supposed to be in the file is not there - or not named correctly. In general, when Acrobat (or the free Reader) complains about a problem with the PDF file, there is actually something wrong with that file. Just because other PDF viewers do not complain about the file does not mean that it's not corrupt.
In Adobe Acrobat Pro, you can actually use the Preflight tool to find out more about what exactly is wrong with this file - the free Reader and Adobe Acrobat Standard do not provide this functionality.