In Colombia use it much the peasants, especially the Boyacá to say or mean what has spoken little matter or is irrelevant. That did not mean nothing, unimportant. Don't worry.
Is an expression that denotes that it said or made not interested in or do not matter. It gives to understand that it is indifferent, has no relationship or is independent of what it is.
And that which!: interpelativa interjection that speaker take on face at the interlocutor the inconvenient or inappropriate words in relation to the issue that we talk about, as meaning: and that have to do with what we are talking about.