How can I translate an extension (module) ? I tried to create the i18n folder and create the it_IT.csv file. But it does not work, how can I do translation?
You will need to create .csv file depending on your locale selected for stores. Then In your custom module you can need to follow below standard for translation.
In php or phtml files:
echo __("String which needs to translate")
In knockout template:
<span data-bind="i18n: 'String which needs to translate'"></span>