The Vietnamese phrase "nửa lời" literally translates to "half a word" in English. It is used to describe a situation where someone understands what another person means without needing a full explanation or a lot of words. Essentially, if someone "nói nửa lời," it means they are able to take a hint or grasp the meaning from a subtle suggestion or implication.
While "nửa lời" primarily means to take a hint, it can also imply a lack of clarity in communication, where not everything is said directly.