What does "ain't" mean here? Also, is it a double negative by using "ain't" and "no" together?
Answer from a Native speaker
"Ain't" is a contraction for "am/are/is not" or "has/have not." It is technically grammatically incorrect and considered to be non-standard English, however, it is still a speaking pattern seen commonly in some parts of the United States. The "no" here does not actually mean "no," it functions as an extra point of emphasis here. "Ain't no preacher" here can be understood as "is not a preacher" in this context. Ex: I ain't no snitch. (I'm not a snitch.) Ex: Ain't nobody here but us. (There is nobody here except us.) Ex: We ain't got no options now. (We don't have any options now.)