Final answer:
A red "X" over a lane signifies that the lane is closed or temporarily blocked and should not be used by drivers.
Step-by-step explanation:
A red "X" over a lane on a road sign typically signifies that the lane is closed or temporarily blocked and should not be used by drivers. This is often seen in construction zones or when there is an accident or obstruction on the road. The red "X" helps to alert drivers to the closed lane and directs them to merge into the open lanes.