The words fleche, flesh sound the same but have different meanings and spellings. Why do fleche, flesh sound the same even though they are completely different words?
The answer is simple: fleche, flesh are homophones of the English language.
Alternative spelling of flèche.
The body as opposed to the mind or soul.
Botany The pulpy, usually edible part of a fruit or vegetable.
The surface or skin of the human body.
Excess fatty tissue; plumpness.
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License, from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").