Brake system failure light and warning

[sassyhillz]

So I have a 2005 Volvo XC90 and my abs lights have been on and off since I first got it without an actual issue with the brakes as far as I can tell but recently will just today my brake light came on and on the messages it's saying brake system failure stop safely yet my brakes still seem to be working fine? Can anybody help me try and figure out what this might be and if it is safe to drive it in the meantime