What part of the human brain is important for executive functions?
If you are asking what is a cortex?
A cortex is the outer layer part of an organ or body part such as a kidney (the renal cortex ), the cerebellum(the cerebral cortex), or a hair(the cuticle).
The Prefrontal Cortex in the human brain plays a key executive functions in humans.
The Prefrontal Cortex in humans is only a few millimetres thick and evolved quite recently in our species at the front of our skulls. It is responsible for all of our key "executive functions" including: decision making, setting goals, deciding good and bad, and moderating social behaviour.
One interesting finding of brain scientists has been that young people (teens and early 20s) often do dumb, risky things because their brain cells connecting the prefrontal cortex and other brain regions are not quite finished development. And so, risky impulses from lower brain regions that in older adults, get vetoed down by the prefrontal cortex, often sneak through in teens! This has lead to a lot of premature deaths and injury in young adults.