Plain English Meaning
Wind blowing from the side pushes the airplane sideways while it flies. Drift and ground track control is the act of noticing that sideways push and turning the nose slightly into the wind so the airplane still travels along the line you wanted over the ground.
Full Definition
The piloting skill of correcting for the sideways push of wind so the airplane follows the intended path over the ground rather than the path it would take through the air alone. The pilot detects drift caused by crosswind and adjusts the airplane's heading into the wind by the amount needed to make the actual ground track match the desired one.
Context Anchor
Seen in ground reference maneuvers, traffic pattern work, and any flight where the pilot must follow a road, runway, line, or planned path over the ground.