Hola Jesús! If you know the "ins & outs" of something, you know how to make it work/ function such as, Computers, Cars...etc. "Ins & Outs" means the detailed fact, the function or the mechanism of something. Hope it helps! Billy

Ins and outs mean all the details. So this sentence means "I don't know all the details of the matter."

It just means details. Imagine knowing something so well that you know the inside of it and the outside of it. Then you would know the "ins and outs" of it.