2005 grand v itart...brake lite comes on. what does this mean.. 25,000 miles

No way to tell.
It would depend on how many times you used the brakes each month.
Average is 25,000 to 50,000 miles but thats just an average range.

depends....... on the drivers habits, if both sides were worn the same, I would say its the driver or the pads used. If the wear is more on one side than the other you may have a caliper problem.

When it needs it. Just because a manual says 100,000 miles on spark plugs and you only have 75,000 on the clock does not mean you can go another 25,000. 75,000 in town miles may be like 100,000 freeway miles.
If there is a servicable fuel filter, I like to change them at least every other oil change. They are $20 for my car but I rather spend that than have trouble with the fuel system.

That is the "Check Engine" light, and it indicates that the car's computer has detected some sort of problem, probably in the emissions system. Make sure your gas cap is tight (yes, something that simple can cause the light to come on!), and take a look under the hood to see if you spot any loose vacuum hoses. If not, you'll need to take it to the dealer so they can use a diagnostic computer to diagnose and correct the problem. At 25,000 miles, it should be covered under warranty. Hopefully it will be something simple!

it possible the front might depending on your driving
habits , but its unlikely the rear does.

valued by its mileage
wires for the spark plugs @ 50,000 miles.
spark plugs @ 100,000 miles
pcv @60,000 miles
air filter when needed or 12 months
fuel filter @25,000 miles

You can go any place like jiffy lube for your Oil and filter change every 4,000 miles or 6 month's which ever comes first. The air filter should be replaced every 25,000 miles and PVC valve or once a year. The transmission, transfer case, front and rear differential should be serviced 80,000 to 100,000 miles or 5 years which ever comes first. The radiator antifreeze if orange service 150,000 miles or 5 years, if antifreeze is green every 30,000 miles or once a year. The spark plugs , wire set good for 100,000 miles. Oh and fuel filter is in the gas tank and a part of the fuel pump so don't let someone tell you that the fuel filter needs to be changed. Change it when the fuel pump fails and that's around 150,000 miles. And last the wipers blade, always replace them in the spring. Good luck and keep me posted, be glad to help. 

WHATIS THE MILEAGE? SOMETIMES THE LIGHT COMES ON WHEN IT IS DUE FOR A WARRANTY SERVICE @ 25,000 OR 50,000 MILES? IS THAT A POSSIBILITY.... THEY ARE WANTING YOU TO DO YOUR REGULAR SERVICE -- ITS A POSSIBILITY

It could cost anywhere from 200.00 to 600.00 depending on the Rotors and if anything else is Wrong.

hmm interesting have you done any wiring to the lights at all?