I met a problem that how to translate the module's phrase into other languages(eg. Japanese).
For example, some code may like this:
app/code/My_vendor/My_module/Controller/i18n/jp_JP.csv
"test","Japanese character"
app/code/My_vendor/My_module/Controller/index.php
......
$form = '<h3>test</h3>';
$this->getResponse()->setBody($form);
......
If STORES->Configuration->Locale
Options is selected with English(United States), it will show "test" to users; if Japanese(Japan) is selected, it will show "Japanese character".
I had seen the tutorial http://devdocs.magento.com/guides/v2.0/frontend-dev-guide/translations/xlate.html but I'm not sure what should I do next.