Imagine you and your friends are playing a game, and you want to keep track of who has what points. You might write down the points on a piece of paper and pass it around so everyone knows the score. A blockchain network works kind of like that, but with a special kind of paper that's impossible to lose or cheat. Instead of a paper, it's a digital ledger, which means it's like a list of all the transactions that have happened.
In a blockchain network, when someone does something, like buy or sell something with cryptocurrency, it gets added to the ledger. But before it gets added, it has to be checked by lots of different people, called "nodes," who make sure it's okay and not a mistake or a cheat.
Once the transaction is added to the ledger, it can never be changed or erased, which makes it really safe and secure. It's like if you write something down on a piece of paper and then put it in a box with a lock on it - no one can change what you wrote without breaking the lock and everyone will know it's been tampered with.
The blockchain network helps us to do things like buy things online with cryptocurrency, which is like a special kind of money that only exists on the internet. It's important to use blockchain networks carefully and wisely, and always to remember that the transactions you make are permanent and can't be undone.