A public sector balance sheet is kind of like a big list that shows how much money a government has, how much it owes, and what it owns. It's like a grown-up version of a piggy bank, but instead of just showing how much money you have saved up, it also shows other important things like debt (which means how much you owe) and assets (which means what you own that is worth money).
So, let's say that the government has a lot of money in its pocket (that's called "cash" on the balance sheet). That's a good thing, because it means they can afford to pay for things they need to do, like building roads or paying teachers.
But what if the government owes a lot of money (that's called "liabilities" on the balance sheet)? That's not such a good thing, because it means they have to pay back all that money they borrowed, with interest. So, it's important for governments to keep track of how much they owe, because if they owe too much, they may not be able to pay it back and could get into trouble.
Finally, the balance sheet also includes a list of all the things the government owns that are worth money (like land or buildings). These are called "assets" and they can help the government raise money by selling them if they need cash.
So, the public sector balance sheet is basically a big list that shows how much money the government has, how much it owes, and what it owns. It's like a piggy bank for grown-ups, but with more important things to keep track of than just coins and bills.