Barcode identification number help please

[OldPostcards]

Hi, I have noticed when editing listings to insert the words 'exempt' and 'unbranded' in our postcard listings that on some of them a barcode number has been put in (automatically, it seems) - 9781877639852.

Is it possible to know why and what this barcode number refers to? I am deleting it on any that I find and inserting the word exempt as I believe that is one of the criteria for the item to show up in google shopping. Also changing upper case titles to lower case. When we used Ebid several years ago I don't think that category existed so it is new to me.

Any help and advice would be much appreciated, thanks!