Confine is all about setting limits. If you are confined to the house, it means you can't leave it. If you're really sick, you might be confined to your bed.
Confine can be used abstractly as well. In writing a term paper, your teacher might tell you to confine your examples to ones that you can support with direct evidence. In the 19th century, pregnancy and childbirth were often referred to as a woman's confinement—a time when she couldn't get up or out.