Web of Things (WoT) is like a web of connected devices, like a big family of different devices all talking to each other. It's like when you have lots of cousins who all know each other and they like making friends with new people.
With WoT, your computer, your printer, your lights, and your refrigerator can all be hooked up to the same web. That means when one device changes (like your toaster becoming hot) it can tell the other devices (like your computer) about it. So your computer can show you a message that your toast is ready.
WoT can also help us use other devices better. Like if you want to dim the lights, you can use your phone to do it instead of needing to go to the light switch. All it takes is for all these devices to be connected to the same web and know how to talk to each other.