Your question is extremely vague. Data can be output to any number of places, including the console (stdout), other forms of graphics, a printer, sound, or to a file.
man has no output of its own. You must specify the name of the manual page you wish to view. For instance, to view the manual for bash, you would use the command man bash.
Typically just the data that the reader encountered. If it's a UPC code the scanner would output the data on the barcode. Most scanners can also be programmed to include some kind of preamble data,...