Oxy-fuel welding and cutting is like using a magical hot wand to stick things together or cut them apart.
The wand has two hoses attached to it - one for oxygen and one for fuel, which is usually a gas like acetylene. When you turn on the wand and light the fuel, it creates a super-hot blue flame that can melt metal!
To stick two pieces of metal together, you have to melt them a little bit so they stick together. You use the wand to point the flame at the metal and move it around until it's nice and hot. Then, you bring the two pieces of metal close together and the heat makes them stick together like glue.
To cut metal, you use the wand to focus the flame on one spot until it gets so hot that it actually melts a hole through the metal! You have to keep moving the wand around to make a straight line.
It's important to be safe when using the wand because it's very hot and can burn things. You have to wear protective gear like gloves, goggles, and a mask to keep yourself safe.