What is the purpose of a pleonasm?

Used accidentally, a pleonasm is just long-winded wordiness, like a sentence that includes far more words than is necessary. Used on purpose, pleonasm is a tool used by writers and speakers to emphasize something or clarify an idea through repetition.

What is pleonasm with example?

/ˈpliː.ə.næz. əm/ the use of more words than are needed to express a meaning, done either unintentionally or for emphasis; an example of this: An example of pleonasm might be "kick it with your feet". There is a looseness in his writing, as in the pleonasm "I myself".