If something or someone is boring, you feel bored.
'Boring' is a synonym of dull, uninteresting, monotonous and tiresome. The feeling of being bored is your reaction to things, people, and situations that are boring.
Does that make sense? Here's a little exercise:
1. This book is ............ . I don't want to read it.
2. I like studying history, but my friends think it's ............
3. I'm ............... . Let's go to beach and have fun.
4. There's not much to do at the park. We're always ............. when we go there.
5. Mr Brown is a really .............. teacher . I fall asleep in his lessons.