Spiritual Meaning:
Talking in dreams signifies spiritual communication, whether that is the passing on of spiritual knowledge or communication from spiritual entities.

Psychological / Emotional Perspective:
We are perhaps afraid of not being listened to properly in waking life and this anxiety can express itself through hearing someone else talking in dreams. It is not necessarily the words that are important, more the sense of what is being said. If we cannot hear them properly we are perhaps not ready consciously to accept the information.

Everyday Material Aspects:
To be conscious of people talking in a dream gives a sense of being in contact with our own ability to communicate. We are able to express clearly what we feel and think, whereas in waking life we may not feel confident. Stopping people from talking means we wish some information to be kept hidden. Translating what is being said suggests we view ourselves as an intermediary, or in some cases the medium for understanding.

You might also like to consult the entry for Hear / Hearing.