If you read your dream symbolically - the mountains can represent struggles, and the giants could be men who are capable of handling the problems. Some could read the dream with erotic undertones, massive giants tilling mother earth, doing with her what they please, which would reflect back on how you feel about yourself as a male (since you don't see yourself as a giant in the dream). Fascinating dream in either case.
One theory is that your brain is trying to make sense of a bunch of random stimuli. Another is that during dreams your brain is trying to process experiences you've collected during your waking hours. Try to figure out for yourself if you've been busy with a lot of fantasy stuff or something. I don't believe dreams have some magical, future-predicting, divine power or something like that, so in that sense I think it means nothing at all.