We introduced the concept of sections in the second chapter
when we broke down a website's structure—your offer, some info about the project, the feedback, schedule, and call-to-action blocks—all of these are known as sections in a landing page.
Sections are useful as each one addresses a specific question—how much does something cost, where are we located, why are we the best—meaning they contain one fully-formed idea. This makes it easier for people to perceive information, as you've brought up a subject (e.g. "Who is this course for"), explained it, and moved on to the next one. Consistency and predictability are two things the human brain loves.