An excitron is like a little particle that gets really excited when it's hanging out in a special kind of material called a semiconductor. Imagine you have a toy that you really like playing with, and when you play with it in a certain room, it gets even more fun and bouncy. That's kind of like how an excitron works!
When the excitron gets excited, it jumps from one spot in the semiconductor to another. This happens because the semiconductor has a special kind of energy level that the excitron really loves to be in. But when the excitron jumps to a new spot, it leaves an empty space behind. This makes another excitron want to jump into that space, and so the "excitement" spreads through the material like a wave.
Scientists are really interested in excitrons because they can help us understand how certain materials work, and they might even have some uses in things like electronics or solar panels!