The Vietnamese phrase "nói sõi" can be understood as "to speak fluently" or "to talk easily," often implying that someone is able to express themselves well without hesitation. It is typically used to describe someone who communicates in a smooth and confident manner.
In more advanced contexts, "nói sõi" can also refer to someone who is persuasive or eloquent in their speech, not just in terms of fluency but also in the ability to convince others or present arguments effectively.