2 stage pump, how is it different from normal pumping

What is a 2 stage pump? I don’t quite understand.. It has 2 cylinders in one? I want to get into pumping, I’m sure I’ll just get a normal cylinder, but I want to understand the variety of tools in the field before I make any purchases.

You must be talking about 2 stage cylinders that are designed to pump both penis and testicles simultaneously. To get started, you just want to get a normal cylinder. This is what a 2 stage cylinder looks like: | LA Pump