The words pleas, please sound the same but have different meanings and spellings. Why do pleas, please sound the same even though they are completely different words?
The answer is simple: pleas, please are homophones of the English language.
Plural form of plea.
To give enjoyment, pleasure, or satisfaction to; make glad or contented.
To be the will or desire of: May it please the court to admit this firearm as evidence.
To give satisfaction or pleasure; be agreeable: waiters who try hard to please.
To have the will or desire; wish: Do as you please. Sit down, if you please.
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.