By a Content Management System ( CMS ) we mean a website that you can add images and text too without and particular technical skills ( you still need to know the basics of using a computer! ), the most common use is to have blog as part of your website. We use WordPress as our CMS, this is the most popular choice by far.
By entry level, we mean that you will get the system installed, but don’t expect any real design effort. There are a selection of themes that are available, to which the design options basically will be limited to adding your logo.
Again it would be expect that you provide images and content and a logo if you have one.
A CMS requires better hosting and some on going maintenance so the running costs are higher than a static site.
Again, this would not include any digital marketing, SEO etc, however having a blog and control over your content gives you or your marketing person more scope to promote the website. Again don’t expect to rank on Google without additional ( possible lots ) of effort.