Do the blind people really dream in their sleep?if they do so what they see?

Everyone dreams (blind people included) and in general, people's dream experience is similar to their waking experience. For those that were blind from birth, they do not have a lot of visual stimuli to draw on for their dreams, so they have dreams that are primarily auditory, tactile (touch) or even involve taste and smell. People who lose their sight very early (before age five) apparently experience no visual imagery in their dreams. Visual imagery is a variable for those who lose their sight between ages five and seven. People who lose their sight after age seven almost always have some level of visual imagery present in their dreams. They've done extensive studies and have also found that REM sleep is disturbed in blind people, so they may actually dream less.

Dreams come from our memories of experiences in daily life so, doubtless, blind people dream in sounds, smells, taste and touch. The eyes, don't forget, are only one of our senses. For most sighted people sight is far and away the most useful but for those without sight, hearing, touch and smell are the most important. Many blind people are not totally without sight and many, of course, have not been blind all their lives. I would expect their memories to give them some visual sensations, even though their eyes no longer can.