I have an idea that it is a Virtualbox, but I would like someone to explain to me a little more about what it is, what it is for, its advantages, disadvantages, among other complementary information that will help me to know what it is a Virtualbox. In advance, thank you very much.
In a few words it is a Software (simulator) (virtual machine) created by Oracle, where you can simulate machines, assigning the desired characteristics, such as RAM, HDD, number of Nuclei, network adapters and a long etc.
Once the virtual machine is created you can install an operating system, either Linux, Windows, Mac and others not so well known to test them or use them for certain tasks as software test that you have developed, as well as running some program that only works on a certain system.
For example, personally I'm a Mac user, and I use virtual machines to use Linux from my mac, windows to create USB bootable, run exclusive windows programs (games). So well, you will have and will be able to execute Operating Systems within your Operating System.
VirtualBox is a software, you can see in wikipedia in Spanish.
What it is and what it is for: (in case I clarify that I did not watch the full video)
link
I think your question concerns a virtualization:
link
The advantage I could mention from my experience (scarce but experience at last):
Speaking in colloquial language, it allows you to keep your operating system 'clean'.
That is to say, if for example, you have to develop an application with a framework of a version 1.0 and another application with the same framework but of a version 3.0, getting those two versions of the same framework to coexist in the same operating system would be at least very complicated. So the most advisable for a case like this is to install two virtual machines and install everything necessary in each one, leaving your operating system clean. Another advantage is that these virtual machines can be shared since they can be downloaded as images ISO.
One disadvantage would be that running or 'turning on' those virtual machines are consuming resources from your 'real' machine or from the host system.
VirtualBox is a software (currently from Oracle and free), that offers you a virtualization . There are other alternatives .
A typical scenario is: one installs the VirtualBox software on a Windows machine (there is also for Linux). In this case, your computer + Windows operating system is known as the "host" machine (host). Then you install or create one or more "virtual machines". These are known as "guest" machines (guests, or visitors), and can be another operating system (such as a Linux) or other versions of Windows (even the same version). The interesting thing is that the "guest" machine is completely simulated ("virtualized") inside the host machine. The "guest" system (Linux, for example), starts as if it were installed on a real disk of a real system, but in reality everything is virtualized. That is, one is running a Windows and ("inside it") a Linux. This is very useful for testing and using different operating systems without having to install it on a different partition of the disk and reboot the system. Of course this requires a lot of memory, and the efficiency will not be as good as in a non-virtualized installation.
One sometimes also uses it to run one Windows inside another (for example, a Windows XP in a Windows 7), either to test or for compatibility problems or because one does not want to "mess up" your system.
Virtualization is also used at the corporate-server level (but not with Virtualbox, which is aimed at end users) to provide VPS , a hosting alternative that is very popular today.