It means you need to perform service 500 miles from now
It will continue to count down as you continue to put miles on the car
This is the suggested service for double wrench display

Double Wrench Service---------------------

Change engine oil, engine oil filter and rotate tires.
Replace dust filter
Lubricate hood hinges, latch and secondary latch.
Reset FSS Display
Check horn, hazard warning flashers, turn signals, indicator lamps, exterior lighting and headlamps (adjust headlight aim, if necessary)
Check windshield wipers and washer system. Replace wiper blades if necessary.
Check seat belts for damage and proper function.
Check hydraulic brakes and parking brake function.
Check fluid levels for hydraulic brake system, power steering system, windshield wiper system and engine cooling system (check corrosion inhibitor/antifreeze).
Inspect front and rear brake pads for lining thickness
Inspect tires for damage, general condition and inflation pressure. Correct if necessary.
Inspect major underbody and underhood components for leakage or damage. (If leakage is found, determine cause and repair)
Inspect condition of front axle ball joints and rubber boots.
Inspect condition of steering components and rubber boots.
Inspect condition of accessory drive belt.
Inspect body for paint damage (every 2 years)
Check chassis and supporting body parts for damage and corrosion (every 2 years)
Retighten steering locking bolts (50,000 miles or 4 years)
Check condition of driveshaft flex discs (50,000 miles or 4 years)
Replace fuel filter and air cleaner filter element (60,000 miles or 4 years)
Change the automatic transmission fluid and filter (80,000 miles). After this changes it is filled for life. Manual transmission comes filled for life from factory.
Replace spark plugs. (100,000 miles or 5 years)
Replace engine coolant using extended life coolant (100,000 miles or 5 years).