The words c's, cees, seas, sees, seize sound the same but have different meanings and spellings. Why do c's, cees, seas, sees, seize sound the same even though they are completely different words?
The answer is simple: c's, cees, seas, sees, seize are homophones of the English language.
Plural form of c.
Plural form of cee., the name of the letter C.
Plural form of sea.
Third-person singular simple present indicative form of see.
Plural form of see.
To grasp suddenly and forcibly; take or grab: seize a sword.
To grasp with the mind; apprehend: seize an idea and develop it to the fullest extent.
To possess oneself of (something): seize an opportunity.
To have a sudden overwhelming effect on: a heinous crime that seized the minds and emotions of the populace.
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").