Okay kiddo, a Kelly Tool is a long metal stick with a handle on one end and a pointy metal bit on the other end. It's used to help drill holes in the ground when people are trying to search for things like oil, water, or other things underground.
The tool is attached to a big machine that does most of the work. The pointy end goes into the ground and spins around really fast like a drill. This helps to break up the dirt and rock so that the machine can dig deeper.
The handle on the other end is used by a person to control the speed and direction of the drill bit. They use it to make sure the drill goes straight down into the ground without going crooked or hitting any obstacles.
It may sound easy, but using a Kelly Tool takes a lot of practice and skill to get it just right. It's a very important tool for people who need to dig deep into the ground for various reasons.