The words prose, pros sound the same but have different meanings and spellings. Why do prose, pros sound the same even though they are completely different words?
The answer is simple: prose, pros are homophones of the English language.
Plural form of pro.
Ordinary speech or writing, without metrical structure.
Commonplace expression or quality.
Roman Catholic Church A hymn of irregular meter sung before the Gospel.
To write prose.
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.