What’s wrong with this sentence?
“You are the very bravest person I know.”
The superlative form of an adjective or adverb is used to describe a quality in the highest degree. A double superlative is formed when the superlative form is preceded by an adverb like very or most.
The quoted sentence has a double superlative because very precedes bravest. To correct the double superlative, remove the unnecessary adverb very.
You are the bravest person I know.