Cell info (not a comment) !

I just downloaded an example of Monthly Budget spreadsheet from Office. I could say I am pretty comfortable around excel, but here is something I never came across before. Once clicking on a cell, a windows pops up with information in regards a cell I am selecting - the thing is - it's not an ordinary comment which is easily editable. I checked everywhere on how to edit this info, I tried to find it's source, but I simply cannot find anything else online other than how to edit comments. Does anyone knows how to edit this info - I must admit - I find it pretty useful... (please find attached screenshot).

Regards,
c4rt0.