You need to understand how the liquid's velocity affects its pressure or head. You have to be able to calculate the head loss through piping, valves and fittings. You must know the difference between gage pressure and absolute pressure. Vacuum is often a part of the calculations so you are going to have to be familiar with the terms we use to describe vacuum. Another name for a hole in a liquid is a bubble so cavitation is all about bubbles forming and bubbles collapsing.
Bubbles take up space, so the capacity of our pump drops.
Collapsing bubbles can damage the impeller and volute. That makes cavitation a problem for both the pump and the mechanical seal. Vapor pressure is about liquids boiling. If you know the temperature of your product you need to know its vapor pressure to prevent boiling and the formation of bubbles. In the charts section you will find a typical vapor pressure chart for several common liquids.