Brake Light Circuit on 1998 BMW 323i

A brake light circuit light came on and I don't know what that means.

Asked by for the 1998 BMW 323i
Check your bulbs- the car measures resistance side to side and compairs the values and will turn that light on if it sees a difference. Poor connections and burned/ damaged wires at the tail light housings are common as well. Good luck!!
im having the same problem bant cant find why???? HELP