A shop's front door, navbar to footer: a photo hero or a product spotlight over rows of new arrivals and best sellers, one of them with a quick add on every tile. Two finished pages.
A section is one full-width band: a hero, a pricing table, a footer. A page stacks several of them into a finished screen, from the navbar to the footer. The sections are the parts, the page is one tested way to put them together.
Koala UI