When you video edit you render new frames etc to create a new video.
GPU stands for graphics processing unit.
Cpu stands for central processing unit. GPU is graphics card and cpu is processor.
Depending on what comp specs you have then it will inevitably show you the outcome of the speed in which your computer processes or renders your video.
To put things in a nutshell computer specs = speed of rendering the video
At this point I can safely assume that you bought this computer from somewhere. I highly suggest you to build a new computer if you are looking to purchase a new computer. This information is very good to know as it can save you quite a bit of money. There are a lot of tech forums of which you could ask for assistance to what to get. There are certain builds or setups that can maximize what you are doing/budget.