Answer:
Key course concepts represent the big ideas in a chapter, section, or course.
Step-by-step explanation:
Let's break it down into definitions.
Key → of paramount or crucial importance
Course → a series of lectures or lessons in a particular subject
Concepts → an abstract idea; a general notion
"A general notion" in "a series of lectures or lessons" of "crucial importance". If we reword it, we understand that "key course concepts" means the main takeaways or notions that you can learn from a section of your textbook or class.