In Harry potter and the Deathly Hallows Part 2, what did Harry see in Heaven?

When Voldemort used avada cadavra on Harry and almost died, he was with Dumbledore in what seemed like Heaven. He was like "dumbledore, what is that?" when he saw a small bloody figure that looked like voldemort in fetus form. I could be wrong but I was wondering what it is? Thank you!