The essence of content management system for websites is to easily carry out modification of content (text and images) without webdevelopment skills.
Thus if the website was built on appropriate data in CMS, you will not have to pay a programmer to change a product description, address or photo.
It is enough just to log in to your admin platform where you can simply change the necessary information. The most widely used open-source (i.e. free) content management systems today are WordPress, Drupal and Joomla.