These are different words with different meanings.
Incorrect spelling - "On" is a preposition, not a number.
"on" is a common misspelling of "one". Always use "one" when referring to the correct word.
Correct spelling - The proper way to spell this word.
"One" refers to the number 1 or a single item.
"one": "One" refers to the number 1 or a single item.
This word is commonly used in everyday conversation and writing.
"Correct:" She has one book.
"Correct:" One student was absent.
"Incorrect:" She has on book.
"Incorrect:" One the table is clean.
A: One.
A: On.
One is a number; on shows position or state.