I sometimes dream within a dream. My most vivid dream about this was when I dreamed some really complex thing involving something coming to destroy our world, and my father (not my IRL father) somehow knowing why but refusing to tell anyone. I went to "sleep" in that dream and dreamed within the dream a memory of my dream-dad having met a girl in his childhood and promising to the girl that they would make their own world together. I woke up from that dream into my previous dream, to which the girl that my father had made the promise to was the same woman who was going to destroy our world, from her grief of having her hopes abandoned by my dream-dad.

I'm not sure what dreaming-within-dreams mean, since I'm not very good at telling the meaning of dreams. They tend to be to me more like small universes in of themselves, so it's strange for me to analyze them.