Simplifying greatly, Singularity is when computers take over.
Or, better when Artificial Intelligence is capable of re-building itself and making itself increasingly more powerful, creating an intelligence that goes far beyond what humans can intellectually grasp, let alone control. It’s a very sobering thought.
Keep an eye on 2040 for that to happen. Statistically I’ll be alive, but on the verge of having too calcified a brain to notice, I hope.