Have you ever talked to someone on the phone or video call, but there was a delay between when you spoke and when they heard you? That's kind of like network delay.
You see, when you send something over the internet, like a message or video, it doesn't just magically appear on the other end right away. It has to travel through lots of different wires and routers before it gets to the person receiving it.
Sometimes, these wires and routers get really busy, like when lots of people are using the internet at the same time. When they get too busy, it can take longer for your message to get to the other person. That extra time that it takes is called network delay.
Think of it like sending a letter. When you put it in the mailbox, it doesn't just teleport to the person you're sending it to, right? It has to go through the postal system and get sorted and delivered. Sometimes, if the postal workers are really busy, it might take longer for the letter to get to the person. That's kind of like how network delay works.
So, network delay is basically just the extra time it takes for your message to get from one person to another because the internet is really busy.