The Kuiper belt is an area beyond the orbit of Neptune that contains large and many small icy celestal bodies left from the formation of the Solar System. The Kuiper belt is before the Oort cloud and is much larger than the asteroid belt.
A red giant is a very bright giant star in its late phase of evolution, when no hydrogen remains in the core and thermonuclear fusion of hydrogen happens in a shell surrounding the core. A red giant is yellow-orange to red in color.
A black dwarf is when a white dwarf cools enough that it no longer emits much heat or light. Since the Universe is approximately 13.7 billion years, no black dwarfs are thought to exist yet, since white dwarfs can still emit heat.