Imagine a giant book filled with all the history of Bitcoin transactions (that's the blockchain). A full node would be like downloading the entire book to your computer. But what if you just need to check a few things, like your account balance? A light node is like a lighter version of the book. It doesn't store everything, but it can still connect to full nodes to confirm information and keep things secure. It's like using a library instead of buying every book you might ever want to read.
