Film geek checking in! This is a Stanley Kubrick movie so the technology he was using was cutting edge, and he was a stickler for quality and detail to almost an insane degree. The first chapter of the movie in Africa was shot on a sound stage if you can believe it. The amazing African backgrounds were actually projected on a screen the actors were in front of. It's a technique called front projection that gives a much brighter sharper image than rear projection. Kubrick would do dozens of takes and use miles of film to capture the perfect moment.

Movie spoilers ahead:
As for the film, it is about aliens causing the evolution from ape-man to humans and beyond. In the beginning, the ape-men are starving, the monolith put there by aliens causes a quantum leap in the intelligence of the ape-men, and they learn how to kill and use tools, killing their enemies and the docile pigs that live with them for food. When the ape-man throws the bone he used to kill his enemy into the air, it spins and becomes a modern weapon, a satellite with nuclear missiles on it pointed at Earth: from the first weapon to the last.

When they uncover the monolith on the moon, the sun hits it and it sends a beam of energy to the monolith orbiting Jupiter, basically telling man "go to Jupiter". That's the sound you hear in the scene of this cinemagraph, the signal. The signal is only sent once man was advanced enough to go to the moon and find the monolith. So they plan a mission to Jupiter.

Once in Jupiter's orbit, the onboard computer malfunctions and kills most of the crew, just leaving one, Dave. Maybe this was by design of the aliens, I don't know. But Dave finds the monolith orbiting Jupiter, which opens the stargate (the color streaks in space). Like the ape-men, Dave's evolution is accelerated and he sees all the secrets of the universe, the big bang, formation of stars and planets, he visits hundreds of distant worlds, at one point he sees the aliens who appear to him as multi-dimensional diamond shapes. The massive influx of information is too much for him, and he "arrives" at the alien's ship or world an old man. The aliens try to give him a home like on Earth with a bed and furniture, but they get some details wrong, like having the light source be on the floor.

While Dave is on his death bed, he sees the final monolith in his bedroom. This completes his evolution into a being of pure energy, soul, or essence, and travels back to Earth as its savior in the form of an infant still in the womb, except the Star-child's eyes are open not closed. In the book the Star-child uses its mind to destroy the nuclear weapons orbiting the Earth, suggesting a new era of peace and perhaps a new chapter for humanity as citizens of the whole universe.