A content management system, or CMS, is the tool you log into to add or change your own website content, like updating your hours, posting news, or swapping a photo, without calling a developer. It separates the words and images you edit from the code that makes the site work, so you can keep your site current on your own.
For a small business, this is the difference between a website that stays fresh and one that slowly goes out of date because every small change means an email and a wait. A good CMS lets a Tuesday edit be live by Tuesday lunch, which keeps your prices, offers, and hours honest.
Not every platform means the same thing here: WordPress and a hosted website builder both give you an editor, with different tradeoffs in control and upkeep. I set up a simple editor for the parts of your site that genuinely change, so you hold the keys, and I write down in plain terms what is yours under website ownership.