Extremely good; the creme de la creme; a real beauty, but not always appropriate for certain things - for example, food can not be described as "bramah". Don't ask me why. This definition seems to be known from SE london area, and from the 50-60's.
"he caught him right in the face with it, man. It was a wicked shot - must have been 50 yards at least; bramah."
This word is a London cockney word used to describe a woman as disgusting ugly.
She is being likened to the bramah cows of India.