I got hold of the user manual for you, but it shows a different light in that place!
Which according to the manual is;
(Translated)
U - Indicator (red) handbrake on and brake system inefficiency, for model 131 Supermirafiori; for other models, it only works in countries where it is mandatory. It comes on if the handbrake is engaged or due to a lack of fluid in the hydraulic system.