The words e's, ease sound the same but have different meanings and spellings. Why do e's, ease sound the same even though they are completely different words?
The answer is simple: e's, ease are homophones of the English language.
Plural form of e.
The condition of being comfortable or relieved.
Freedom from pain, worry, or agitation: Her mind was at ease knowing that the children were safe.
Freedom from constraint or embarrassment; naturalness.
Freedom from difficulty, hardship, or effort: rose through the ranks with apparent ease.
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").