I think that it's due a brake fluid change if I remember correctly
I think it's the brake fluid renewal service light.
Did a quick search on the web and found this info to reset it. Not sure if this will work but at least you will know what to look for
1. Ignition key to position 0 (off)
2. Hold trip meter button (the left button)
3. Ignition key to position 1. The display will show: "test 1"
4. Keep holding the trip meter button until the the display shows: "reset inspection" or "reset oilservice"
5. Release the button
6. Press and release the tip meter buton once. The Display will show the square clock symbol and the month the fluid change is overdue on. I can't remember if the date format was mm.yy or yy.mm
7. Press and hold the trip meter button until the display is showing a flashing "reset". Then release the button. "Reset" will keep flashing.
8. Presss and release the trip meter button once. The display will show the square clock symbol and the month for the next fluid change in 2 years time in the format mm.yy or yy.mm
9. Press and hold the trip meter until "End" is displayed
10. Let go of the button and turn ignition to 0 (off). The clock symbol will not show again until the next fluid chnage is due
2000 E46 330i SE Manual