We anticipate that some gnu.org translators will find this format odd or inconvenient, if they never happened to work with PO files before7. Don’t worry, you will soon get accustomed to it. It is the established format for translations in the Free World, and if you have any problems, other translators will help you.
The most efficient way to edit a PO file is using a specialized PO editor, because each of them represents and treats gettext messages in a consistent and predictable way. It is possible to edit a PO file with an ordinary plain text editor, but extra effort would be necessary to make the result valid.
Note that recent versions of some PO editors (both offline and web-based) offer access to various translation services that do machine translation for their users. Using a machine translation service is a clear example of SaaSS (see Who does That Server Really Serve?), so please don’t use such editors unless they only submit requests to your (or GNU project’s) own servers.
Here is a list of widely used PO editors we can recommend:
M-x po-mode RET. On some GNU/Linux distros such as gNewSense, PO mode is available in a separate package,
gettext-el. See Emacs’s PO File Editor in GNU gettext tools.
wxWidgetsgraphical toolkit. See http://www.poedit.net.
Also, that Pootle server has a simple facility to preview your translations as they will appear on www.gnu.org. In order to test a page, log in the server and visit https://chapters.gnu.org/pootle/gnun/test.html. That page contains a menu to upload a PO file; then the server will generate the translation and show you the build log (including errors), and the generated web page (when the build is successful).
For detailed information about editing PO files, see Working with PO Files in The GNUnited Nations Manual.