When i drive there's hissing sound,but when i press the brake it stops

One morning, when starting the engine, a kind of whistle was heard and an orange warning symbol appeared, indicating, according to the manual, that the rear stop light was damaged. I replaced the gadget which is similar to a pivot and the rear lights turned on, but occasionally the warning indicator appeared just as well. Today, when starting the engine, the same symbol turned on but now the low beam headlamps are not working. What might be happening? Thanks beforehand for your comments.