Flux-cored arc welding is a type of welding that works a bit like glueing things together with a hot metal glue gun. You use a special tool called a welder to melt a metal wire that you stick to the thing you want to glue together.
Now, this metal wire has a special powder inside of it that melts along with the wire as you use the welder. This powder is like a magic helper that keeps the melted metal clean and makes it stick really well to the thing you want to glue together.
When you use a welder for flux-cored arc welding, you make an electrical circuit. The welder puts out electricity that makes a little lightning bolt between the metal wire and the thing you're trying to glue together. The lightning bolt gets really hot and melts the metal wire and the special powder inside at the same time.
When it's done, the melted metal cools and hardens quickly, and you're left with a strong bond that holds everything together. This is how you can make things like steel frames and buildings, car parts, and even sculptures!