This is the 74th most frequent Vietnamese word.
nếu
"If."
Here, 'nếu' serves to introduce an indirect question, representing uncertainty or possibility.
Tôi không biết nếu cô ấy sẽ đến.
I don't know if she will come.
In this case, 'nếu' conveys a conditional premise that affects the decision or action taken.
Bạn nên hỏi cô ấy nếu bạn không chắc chắn.
You should ask her if you are not sure.
In this sentence, 'nếu' is used as a conditional conjunction, introducing the condition under which the following action will occur.