The computational power of the human brain is the number of operations per unit time performed by the adult brain of a typical human.
Further reading
Aguirre, Anthony (2019) How many FLOPS for human-level AGI?, Metaculus, March 13.
Sandberg, Anders & Nick Bostrom (2008) Whole Brain Emulation: A Roadmap, Oxford: Future of Humanity Institute.
Carlsmith, Joseph (2020a) How much computational power does it take to match the human brain?, Open Philanthropy, September 11.
Carlsmith, Joseph (2020b) Discussions with Dr. Paul Christiano, Fall 2019-Spring 2020, Open Philanthropy.