The words brewed, brood sound the same but have different meanings and spellings. Why do brewed, brood sound the same even though they are completely different words?
The answer is simple: brewed, brood are homophones of the English language.
Simple past tense and past participle of brew.
To hover envelopingly; loom.
To sit on or hatch eggs.
The young of certain animals, especially a group of young birds or fowl hatched at one time and cared for by the same mother. See Synonyms at flock1.
The children in one family.
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").