Adolf Frederick was a man who was very important in Sweden a long time ago. He was called a "king," which means he was in charge of the country. Like when you play pretend and you are the "king" or "queen" of your playtime.
Now, even though he was in charge, Adolf Frederick didn't have as much power as the kings and queens of some other countries. He had to follow rules and he needed help from other people to make decisions.
Adolf Frederick was also very famous for something kind of funny. He really loved to eat a dessert called semla. A semla is like a sweet bread with cream inside. It's kind of like a jelly donut but without jelly, and it's very yummy. Adolf Frederick loved semla so much that he would eat a LOT of them every year on the same day, which was called "Semla Day."
One year, on Semla Day, Adolf Frederick ate too many semla and got really sick. He didn't feel good and had trouble breathing. Sadly, he died that day. So, even though Adolf Frederick was an important man, he's also remembered for his love of semla and how he ate too much of it. That's why people sometimes say it's important to have balance in what you eat and not have too much of one thing.