Okay kiddo, have you ever played with a Russian doll that has smaller dolls inside it? It's called a Matryoshka doll. Similarly, holons are like Matryoshka dolls - they are parts that make up a whole and can also be seen as a whole that has parts.
In philosophy, a holon is a thing or a system that is both a whole and a part at the same time. It means that it has its own identity as a whole and it is made up of smaller parts that have their own identity as well.
Imagine a bicycle - it has a frame, a chain, pedals, and wheels. These are all parts of the bicycle that have their own identity and can also be taken apart. But, the bicycle as a whole can also be seen as a holon because it has its own identity and purpose.
Holons can exist on many levels - from small things like atoms that make up molecules, to big things like ecosystems that consist of many different living and non-living parts.
So, in summary, a holon is kind of like a Matryoshka doll - it's a thing or a system that is both a whole and a part at the same time, and it can exist on many different levels.