What does it mean to dream about people that are dead and they are moving about and talking?

This could mean many different things, depending on who the dead are and what they are saying. It is quite normal to dream of friends and loved ones who have passed away, and dreams are often part of the grieving process. Close human relationships do not necessarily end with death.

... However, dreams of decomposing dead bodies becoming animate and speaking would suggest that issues thought to be "dead and buried" in the past might be coming back to cause problems in the present.