The gpg flags --export and --gen-revoke are examples of gpg commands; they tell gpg what to do. To tell gpg how to do things, you can often precede your commands with options. Both --armor and --output are examples of gpg options; they tell gpg to write its output in the Armored ASCII format and to write to a file rather than the standard output, respectively. The --output option requires you to specify a filename (with or without full path), but the --armor option has no arguments.
Armored ASCII (whose filename suffix is .asc) is the most portable data format gpg uses, in contrast to gpg's default binary format (which uses the filename suffix .gpg). Unlike this binary format, Armored ASCII can be copied and pasted, into e-mail for example. If saved to disk, an Armored ASCII file is identical to a normal text file. For this reason you'll probably wish to use Armored ASCII most of the time when exporting, backing up and transmitting keys.
I mention this here because the other way to specify gpg options is in the options file located in your .gnupg folder. To change gpg's default data format from binary to Armored ASCII, add the following line anywhere in your options file:
In general, any option and its desired argument(s) may be added to options in this way, i.e., minus the leading “--” and on its own line. Options specified in a command line take precedence over options set in the options file. See the gpg(1) man page for a complete list of gpg options.