it has a sticky handbrake switch
This light is used for 2 different purposes.(1) If the brake fluid is low,this light will come on.(2) light will come on when you engage the parking brake.
Check your master brake cylinder, as the warning light will come on if the fluid level is low. If that is OK, you probably need to change your brake pads.
If your handbrake is on or if the brake fluid level in the brake master cylinder in your engine compartment is LOW , the " brake " light in your dash will light up
handbrake light
The handbrake light is also the 'low fluid' warning light. It is connected to the handbrake as that ensures that it is checked every time you use the handbrake. If it remains on all the time, then check the brake fluid and top up if required. If the fluid is ok then it is probably the switch on the lever and is adjustable.
Because you probably still have your handbrake on. If not, than you need to see the car-doctor.
Because the switch has either failed or come off it's mounting. There is an outside chance, if there has been work around the handbrake lever/centre console, that the switch wires might have become trapped and could be shorting out.
it means your handbrake is on
usually a sticky switch on handbrake, had any welding recently ?, worn shoes ?
your switch that tells the car that the brake is off is defective
On a Saxo, the handbrake can sometimes come loose and needs to be tightened. To do so, first turn the engine on and place your foot on the brake. Push in the handbrake button and then pull up on the handbrake until tension is felt. Repeat as needed.
Release the handbrake