Well kiddo, Pollyanna is a character in a story who always tries to find something good in everything, even when things are not going very well. She looks for what's called "the silver lining" in every situation, even if it's really hard to find.
It's kind of like when you're stuck inside on a rainy day and can't go play outside. Instead of feeling sad about not being able to go out, you might choose to play board games or build a fort inside. That's being a bit like Pollyanna, finding the good even in a not-so-good situation.
Some people use the word "Pollyanna" to describe someone who always tries to see the positive in things, even when it might seem impossible. It's a really nice way to live because it helps you stay happy, even when things get tough.