If the fuse is OK, then you need to check the brake light bulbs and replace the bulbs if necessary.
Check the brake light switch. To do this, remove the cover located above the brake pedal. Disconnect the plug connector at the switch.
Turn on the ignition.
Use a short auxiliary wire to make a jumper between both contacts of the plug removed from the switch. If the brake light comes on, the brake light switch is faulty. Replace the brake light switch.
Otherwise, it is necessary to check the lighting system module.
(Information taken from this resource BMWMAN.RU)