Seeking Advice on 2007 Volvo S60's Speedometer Warning Light and Low Brake Fluid Issue

Warning light in the speedometer of the vehicle

Hey folks, I've got a 2007 Volvo S60, diesel model, playing up lately with a warning light on the speedometer. I suspect the brake fluid might be low. Anyone faced a similar problem? Can you share your experiences and solutions? How did your local mechanic resolve it? Really appreciate any tips or suggestions!

(Translated from German)