Final answer:
The white "X" sign with "RAILROAD CROSSING" warns drivers to look, listen, and prepare to stop if necessary at a railroad crossing, proceeding with caution to ensure safety.
Step-by-step explanation:
The white "X" sign with "RAILROAD CROSSING" indicates that you are approaching a railroad crossing.
This sign serves as a warning to look, listen, and prepare to stop at the crossing, if necessary, to yield to any oncoming trains.
It is not a directive to immediately stop, but rather to proceed with caution and be ready to stop if you see a train approaching or if there are signals indicating that a train is imminent.