Okay kiddo, so Pablo Picasso was a famous artist who made lots of paintings that people still look at and enjoy today. But there was a time when he painted a lot of pictures using mostly the colors blue and blue-green. This time is called Picasso's "Blue Period."
Now why did he do this? Well, sometimes artists use colors to show how they're feeling inside. And during the Blue Period, Picasso was feeling pretty sad and lonely. He had lost some people he loved, including a close friend, and he was also struggling to make enough money to live on. So the paintings he made during this time often showed people who looked kind of sad or tired, or who were sitting or sleeping alone.
The colors he used, like blue and green, can sometimes make you feel calm or sad. So when people look at Picasso's Blue Period paintings, they might feel those same feelings too. But even though the paintings are a little sad, they're also really beautiful and interesting to look at. And that's why we still talk about them today, so we can remember how Picasso was feeling and how he used his art to express that.