When you are bored, nothing is engaging you. If you're on a long flight, you forgot your book, and there's no movie, you might become bored.
The adjective bored comes from boredom, the state of being where nothing is interesting or exciting. If you only understand English, you'll probably get bored quickly listening to German talk radio. It's hard not to be bored by a six hour bus ride on a featureless interstate highway. If you are deeply, spiritually bored by the world, you are suffering from ennui — that's boredom in French!