Okay kiddo, so let's start with what a VPN means. VPN stands for Virtual Private Network. A virtual private network is like a secret passage that helps you connect to the internet safely and securely. A mediated VPN is one in which a third party controls the VPN connection and directs the traffic between two or more endpoints.
Think of it like this, when you want to connect to the internet through a VPN, you can think of it like you want to send a secret message to your friend. You don't want anyone to read it, so you tell your other friend, let's call him the mediator, to help you deliver the message. The mediator will make sure that your message is encrypted and safe while it travels between you and your friend. He will also make sure that no one else can read it or tamper with it.
In the same way, in a mediated VPN, the third party service acts as the mediator. It encrypts and secures the data sent between two endpoints, like your computer and your office's server. So, when you send data through a mediated VPN, it is protected and secure from any hackers or snoops who want to steal your information.
So, in summary, a mediated VPN is a way to safely and securely connect to the internet by using a third party to encrypt and protect your data. It's like having a secret passage that only you and your friend can use, and no one else can see or tamper with your messages.