The words herds, hurds sound the same but have different meanings and spellings. Why do herds, hurds sound the same even though they are completely different words?
The answer is simple: herds, hurds are homophones of the English language.
Plural form of herd.
Third-person singular simple present indicative form of herd.
The coarse part of flax or hemp; hards.
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.