What does "Bueno, pues nada" mean in English?
And how do people usually use it?

Question

What does "Bueno, pues nada" mean in English? 
And how do people usually use it?

Answer

I have heard this said when a person has gotten lost while talking, in other words, they stumble and forget what it is they are talking about, or suddenly want to switch topics....  you can understand it perhaps as a "well, i don't know....."

Answer

That means something like: "Well.. nothing"