What kind of speech is and and by?

The phrase "and and by" appears to be a typographical error or an incomplete thought. If you meant to ask about a specific type of speech, such as "and" as a conjunction or "by" as a preposition, both serve different grammatical functions. "And" is used to connect Words, phrases, or clauses, while "by" indicates a method or means of doing something. Please clarify if you meant something else!