Here's a quick overview of how a water softener works:
Hard water enters your home from your main water pipe or well, and travels to your water softener. Ionized resin in the softener tank attracts and holds onto the minerals that make your water hard (calcium, magnesium, iron, lime and more), removing those minerals from the water. Softened water exits the tank and flows to the plumbing throughout your home. Soft water makes your soap more sudsy, keeps your pipes and fixtures free from scaling and build-up, and helps to make your skin cleaner when you shower.