It is not clear whether you are discussing something happening in the movie or the viewers comments about certain characters. If someone says, "The man knew how to talk" I think it means the person's speech is carefully worded taking into the place, audience and so on, and thus it is a compliment for his speech , but such a speech need not necessarily be honest or straight forward.
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jiangyuemingThen another person said "The man knew how to talk". In this context, is it a complement for his good speech?No, it is not likely that it is a compliment for his good speech. You have given some context, which is a good idea, but unfortunately not enough. Therefore, we have to guess more about the context.