avast! Home/Pro is currently provided in the following languages:
- English (program + help)
- Czech (program + help)
- Spanish (program only)
- Italian (program + help)
- Dutch (program only)
- German (program only)
- Hungarian (program only)
- Polish (program + help)
- Portuguese (program + help)
("Program only" means that the help files are in English).
If you're interested in a supported language, you can either download the installer for the particular language, or add the language to an existing avast! installation using the Control Panel / Add/Remove Programs / avast! Antivirus / Change or Remove / Change.
Some more languages will appear, hopefully.
I guess this is not exactly a "translation forum", but if you have any questions, feel free to ask.