The words whit, wit sound the same but have different meanings and spellings. Why do whit, wit sound the same even though they are completely different words?
The answer is simple: whit, wit are homophones of the English language.
The least bit; an iota: doesn't give a whit what was said; not a whit afraid.
The natural ability to perceive and understand; intelligence.
Keenness and quickness of perception or discernment; ingenuity. Often used in the plural: living by one's wits.
Sound mental faculties; sanity: scared out of my wits.
The ability to perceive and express in an ingeniously humorous manner the relationship between seemingly incongruous or disparate things.
Definitions 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").