Alright kiddo, imagine you are playing with your favorite toy car in your bedroom. Your friend outside wants to play with you, but the door is locked, so they can't come in. The only way to play together is if you bring some of your toys outside to the porch, so you can all play together.
That's what a NAT (Network Address Translation) does in your computer or router. It is like your bedroom door and your friend is the internet. When your computer is connected to the internet, it gets a unique address called IP address. It's like your home address, but for your computer.
But sometimes, your computer or router has many devices connected to it and they all want to access the internet at the same time. It's like if you have many toy cars you want to play with at once. To do that, you need to share the porch with your friends so you can all play together.
That's where NAT port mapping comes in. Port mapping assigns a specific toy to each friend, so they can all play together without fighting over the toys. These specific toys are called ports, and they have numbers assigned to them. So when your computer sends an internet request, it adds the port number to the IP address, like a label on a package that tells the internet where to send it.
But there's still the problem of your bedroom door being locked. In this case, the NAT uses a special trick called port forwarding. It takes the request from your computer, adds a new toy car port, and sends it to the internet to be played with by other people.
So in summary, NAT port mapping protocol is like sharing your toys with your friends on the porch. It assigns specific toys (ports) to each friend to avoid fighting, and uses port forwarding to let them access it even if your door is closed.