An exchange is a transfer of two things, one for the other, as for mutual consideration. In dreams, it is often interpreted to mean that you are exchanging something with someone else. If you are giving something and receiving nothing in return, then it may signify the fear and worry of being taken advantage of by others. If you are taking from someone else and not giving anything in return, then it may represent self-indulgence and greed.
Exchange in a dream may also represent the idea of sharing and compromise. Sharing would be friendly generosity, and compromise would be the willingness to give up something for the sake of making things work.