VPS (Virtual Private Server) hosts are comprised of several isolated server environments hosted on one larger partitioned server. Essentially, a VPS functions as its own independent server giving each user root access and full control over everything running on their environment.
Fully managed support by HostGator is dependent upon a control panel. A VPS with cPanel will come with fully managed support, while a VPS without a control panel will have limited support, only covering issues such as hardware failure, major operating system issues, etc.
Now that you know what a VPS is, you can review other features and functions by reviewing the VPS Getting Started Guide.