Okay, so have you ever met a really bossy person who thinks they're the best and loves to control everything around them? That's kind of what we mean by "Napoleonist Syndrome" - it's a term used to describe someone who acts like they're a powerful ruler, always in charge and better than everyone else.
Now, who was Napoleon? He was a famous general who lived a long time ago in Europe. He was known for leading armies into battle and taking over lots of countries. He was also known for being short, but that's not really important right now.
So, the idea of "Napoleonist Syndrome" comes from the way Napoleon acted - like he was the most important person in the world and could do whatever he wanted. People who act that way today might be called "Napoleonists" because they have a similar attitude.
It's not really a good thing to have Napoleonist Syndrome, because it can make you seem arrogant and insensitive to other people's feelings. It's better to be kind and considerate of others, even if you are a natural leader who likes to take charge.