To add translation csv file in magento2, you just need to add a folder named:
“i18n” inside your module’s folder, i.e.
Then create a csv file with name of language code.
for english (United state) => en_US.csv
Inside csv file you just need to add words which you want to translate, in following manner:
“<word in english language>”,”<word in language to convert>”
Now, define your word at place of use:
<?php echo __('Store Title');?>
Hope it helps !