WordPress is a user-friendly content management solution for smaller scale websites. It was originally built as a blogging tool to help bloggers create beautiful websites that were easy to update but now has expanded way beyond that.
It is very user-friendly for the content manager and often there are plugins that add various functionalities that are also easy to navigate.
If you are having trouble figuring out how to edit, update or add to a WordPress site, there is most likely some documentation out there to help you. Each plugin should come with documentation on how to use it and any Core WordPress functionality is documented on the WordPress website.