Not is a function word (adverb) used to negate a word or a group of words.
I have time to do it.........I do not (have any time to do it.).
I have eaten my dinner........I have not (eaten my dinner).
I love you because you are beautiful.......I love you, but not (because you are beautiful).
'No' can be an adjective meaning 'not any' or 'harldy any' or 'not a'.
I have no time.
I have no money.
There is no answer to that question.
She is no doctor.