On my Note 8 you can translate to Vietnamese but not from it, strange.
Pull the pen out and select "translate" from the pop-up menu. Find the text you want to translate, for example a page on a website. Point your pen to the word on the page. You will see another pop-up on the the top of the page with a choice of languages. Select the language. Now when you point the pen to the word you will see the translation above this word.