As a verb:
* "The prisoner was confined to his cell." (meaning he was kept within the cell's boundaries)
* "The doctor confined her diagnosis to a simple explanation." (meaning she limited her explanation to the most important points)
As a noun (usually plural):
* "The confines of the small apartment felt oppressive." (meaning the limitations of the space were uncomfortable)
* "She felt trapped within the confines of her marriage." (meaning she felt restricted by the limitations of her relationship)