Siri now allows you to translate words and phrases from English into a limited selection of languages, which are French, German, Spanish, Italian and Mandarin Chinese. Admittedly it's a short list, but Apple plan to release further languages over time
Right now translation in the reverse direction isn’t available.
On release translate only worked when Siri was set to English (United States), but subsequent updates added the feature to additional languages, such as English (United Kingdom).
So if you find the translate feature doesn't work with your default language settings, you'll need to set them to English (United States).
How do I say where is the nearest hotel in German?
Translate I would like to book a table for two at your restaurant please into French
Siri will respond by reading out the translation and displaying the text on screen. To play the audio again, press the the play button located at the bottom right of the translation.
You can also follow up your initial translation request by asking for the same phrase in another language.
For example, while the results screen is still displayed, say:
Siri will then update the audio and text phrase.
Despite its obvious limitations, translation using Siri is still impressively accurate and well implemented. As long as Apple continue to add further languages and include reverse translation in the future, it can only grow in usefulness.