Plain English Meaning
Reading the VOR needle correctly so you know where you are compared to the course you've chosen. The needle tells you which way the course is, the flag tells you whether the station is ahead of you or behind you, and together they place you in the picture.
Full Definition
The skill of reading the Course Deviation Indicator (CDI) needle on a VOR display to determine the aircraft's position relative to the selected course. The pilot interprets three pieces of information together: the OBS (Omni Bearing Selector) setting, which course the needle's deflection direction (left or right), and the TO/FROM flag, to establish where the aircraft is in relation to the and the chosen .