WordPress is a light-weight, customizable system for building websites because only core functionality is built in. That is what makes WordPress stand out from many of the CMS solutions. You add the plugins you need to build the functionality you are looking for in your site.
There are thousands of plugins made for WordPress, but choosing the right ones isn’t easy.
The wrong plugin can break some of the functionality of your site or even render your site completely unusable. That is the good and the bad about open source projects. Anyone can build a plugin and make it available, there is no central controlling group that determines what plugins should be developer, how they should be developer and testing them.
But that is also the magic of open source, because it fosters creativity and innovation.
You can go it on your own and try to guess what plugins are right for your site, or have a professional on your side.