Dedicated server is a physical server that you can lease from the hosting provider. This allows you to have full control over the server including the choice of operating system, hardware etc. You DO NOT need a dedicated server if you are just starting out. Once your site is receiving a significant amount of traffic, only then you should consider upgrading to a dedicated server. WPBeginner runs on a dedicated server by HostGator. If you do not employ a system administrator or have no experience with servers, then we recommend that you get a managed dedicated server. WordPress hosting providers who offer managed dedicated servers employ full-time system administrators that maintain your servers. Along with doing software updates, they also do server monitoring, offer phone support etc. Most top websites use clusters of dedicated servers.
For packages supporting unmetered disk space or data transfer (bandwidth), we do not have defined limitations. These resources are "unmetered", meaning you are not billed according to the amount of disk space or bandwidth used. While of course these resources are not infinite, we believe our customers should have all the resources necessary to build an online presence and 99.95% of customers will have more than enough disk space and bandwidth to meet their needs.
Web hosting services offer varying amounts of monthly data transfers, storage, email, and other features. Even how you pay (month-to-month payments vs. annual payments) can be radically different, too, so taking the time to plot exactly what your company needs for online success is essential. Many of these companies also offer reseller hosting services, which let you go into business for yourself, offering hosting to your own customers without requiring you to spin up your own servers.