The words hours, ours sound the same but have different meanings and spellings. Why do hours, ours sound the same even though they are completely different words?
The answer is simple: hours, ours are homophones of the English language.
Plural form of hour.
Used to indicate the one or ones belonging to us: The original of the painting is ours. Their children are grown, but ours are still young.
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.