Plain English Meaning
CRS is the heading line you've told the navigation system you want to fly along. It's the path you've picked; the instruments then show whether the aircraft is left, right, or on that path.
Full Definition
On a navigation display or HSI, CRS is the label for the selected course — the desired track over the ground that the pilot has set, typically using a course selector knob. The CRS value is shown in degrees and tells the navigation system which inbound or outbound radial, bearing, or final approach course the aircraft is trying to fly.
Context Anchor
Seen on instrument displays, course knobs, and navigation pages when setting or checking the selected course during .