Hero
The hero is the big first area at the top of a page: one headline, one short line and one button.
In a simple example
A cake shop opens with a large photo, the words Fresh cakes every morning, and a button Order today.
Why it matters to you
People decide in seconds whether to stay, so the hero must say what you do and what to press.
Do not confuse with
Hero here is a design word. It has nothing to do with a person or a story hero.