The girl he secretly loves is visible but unattainable.
Tips
history
Recorded in Song Yu 宋玉's 《高唐赋》 (Warring States) and later 《楚辞·九辩》. The phrase describes something seen from afar but unreachable. Used today almost interchangeably with 可望而不可即.
usage
即 here = to approach / draw near (classical), not 'that is.' The variant 可望而不可即 / 可望而不可及 is equally common.