The words bean, been sound the same but have different meanings and spellings. Why do bean, been sound the same even though they are completely different words?
The answer is simple: bean, been are homophones of the English language.
Any of various New World twining herbs of the genus Phaseolus in the pea family, having leaves with three leaflets, variously colored flowers, and edible pods and seeds.
A seed or pod of any of these plants.
Any of several related plants or their seeds or pods, such as the adzuki bean, broad bean, or soybean.
Any of various other plants or their seeds or fruits, especially those suggestive of beans, such as the coffee bean or the vanilla bean.
Past participle of be.
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.