A virtual server, sometimes called a virtual dedicated server or virtual private server, is a server that looks and acts like a dedicated server, but which is actually a partition of a larger host which runs several virtual servers. The virtual servers do not have any hardware of their own but act as if the portion of the hardware allocated to them from the host is their hardware.

A virtual private server gives you the features and functionality of a dedicated server without the cost of building and maintaining one. If you want to host unlimited domains, get complete control of your environment and run your own applications, then you will benefit from having a VPS. Furthermore, a VPS provides the ability to manage your dedicated environment through SSH and a control panel. These control panels enable the root user to perform actions to their VPS immediately, without having to contact support to have a technician to complete any necessary requests.

A VPS removes the limitations of shared hosting by giving you the power and flexibility of a dedicated server with your own set of services and customizable disk space. Shared hosting is limited in comparison because its users do not have root access and software configurations cannot be customized.

Yes, you get full access to your virtual server so you can install without limit all software you wish for.

You get full access to your virtual servers. For Windows servers, you get administrator access, and for Linux servers root access.
So, you get full control over the servers enabling you to install software and use the server for your applications.