Translation:She smiles at me and that makes me happy.
As a Vietnamese native speaker, at first, I also thought it should be "She smiles with me". I had to look up in some dictionaries and found interesting results, and it seems like the answer suggested by Duo is correct.
Oxford Advanced Learner's Dictionary gives this example: "She smiled at him and he smiled back", which can be quickly translated into Vietnamese as "Cô ấy cười với anh ta và anh ta mỉm cười đáp lại". (https://www.oxfordlearnersdictionaries.com/definition/english/smile_1?q=smile)
The English-Vietnamese Dictionary 2005 edition, published by Vietnamese Institute of Linguistics, which is now made available online through Laban dictionary website, gives another example supporting the use of "smile at" as "cười với": I smiled at the child and say "Hello" - Tôi mỉm cười với cháu bé và nói: "Chào cháu". (https://dict.laban.vn/find?type=1&query=smile)
I also realized the difference between smile at & laugh at. =))) Hope this helps.
You can see more examples and translations using "laugh at" here ( https://dict.laban.vn/find?type=1&query=laugh ) Scroll down till you see laugh at sb/sth and there are some better translations for "laugh at" as its meaning changes with context. "Cười vào mặt ai" is rather a colloquial and informal phrase, "cười nhạo" is a much more formal (and may be better) translation. By the way you can always look up Vietnamese translations for words and even phrasal verbs on this online dictionary, though it might lack a lot of current English usages as it was based on an outdated version of OALD.