Okay, kiddo, so Fiore dei Liberi was a man who lived a long, long time ago in Italy. He was really good at fighting and wrote a book about how to do it.
This book was special because it had lots of pictures to show people how to fight like he did. He called it "Il Fior di Battaglia," which means "The Flower of Battle" in Italian.
Fiore dei Liberi was really good at teaching people how to fight and he had lots of students who learned from him. They would practice together and try to get better at defending themselves and attacking their enemies.
Even though Fiore dei Liberi lived a long time ago, people still study and learn from his book today because it's very helpful if you ever need to protect yourself. So, you see, even though he's not around anymore, Fiore dei Liberi left a big impact on the world by teaching people how to be strong and brave.