1998 Ford Explorer consel warnings

That is just indicating to you your washer fluid reservoir is empty or low. It is located on the passengers side of the vehicle in the engine compartment. There are 2 reservoirs windshield washer fluid and engine coolant the one closest to the fire wall is for the windshield washer fluid.

If there is plenty of fluid present in the reservoir the sensor inside the reservoir located near the bottom needs replacement. Replacement of the sensor would require removal of the washer reservoir to gain easy access for removal and replacement.
Rick