Storefront product pages, navbar to footer: the buy box beside a gallery, a photo grid or an edge-to-edge photo rail, then a grid of related products to keep shopping from. Three 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