One of the main reasons WordPress is the go to website solution for beginners is because of it's intuitive user interface. The WordPress dashboard which contains a window on the right hand side and a menu on the left hand side makes it really simple to make adjustments and navigate throughout your websites back end.
WordPress Plugins are additional features you can install on your WordPress build to add functionality to your website. Installing WordPress plugins is as simple clicking install and within seconds you can start adding complex functionality to your website. WordPress plugin allow give you the option to easily implement things likes forms and login systems.
WordPress Themes, very much like WordPress Plugins, are additional pieces of code you can add to your website but instead of adding some sort of tool or functionality to your Wordpress website it adds visuals and uniformity to give it a more unified and professional look. WordPress Themes are extremely powerful tools because not everyone has the time to learn how to design a website or the money to hire a designer to do it for them but by adding the right WordPress Theme you can give your website a professional grade look that sends the right message and let's you focus on what really matters to you within seconds.
One of the realities as a website owner you'll eventually run into are technical issues. As powerful and helpful as these communication tools are they can occasionally be a bit sensitive and malfunction. The benefit of working with WordPress is that, due to its popularity, there are countless tutorials covering WordPress in depth available throughout the internet for free when problems arise.