Hey Lucamar,
Depends a lot on what they offer you. If they just say: "OK, here is your 'machine', do what you will with it" (i.e. they give you an empty "machine"), then think of what you would have to install in a real machine, say, at your home, and do the same for the virtual one: install OS, install database server, install web server, install your app and you're (basically) done.
The VPS offer is just that: You get a virtualized hardware that you can control via a web panel and you just SSH or VNC in and presto done, you have a full server for you to play around.
No limits and no hardware involved. It's all virtualized on top of a massive machine with a SHIT ton of RAM and a TON of cores
But to the customer, it's just like having a machine in your office/living room and you SSH in.
This of course has nothing to do with a CPanel webhosting. This is a solution on top of Apache's Virtual Hosting for web and you share all the resources of a single machine with other clients.
On a VPS you are master of your server and don't share the OS, you just share the Iron(Hardware), but in all aspects, it's just like a machine next to you.
I dunno if that makes sense. I'm probably quite bad at explaining these things
Cheers,
Gus