The exchequer of pleas is like a big piggy bank where the King used to store all the money that people paid him. When people wanted to borrow money from the King, they would have to pay him back with interest, just like when you borrow a toy from a friend and give it back with an extra toy as thanks. All of this money would go into the exchequer of pleas.
When people owed the King money or did something wrong and needed to pay a fine, they would have to go to the exchequer of pleas to pay up. This is just like when you owe your parents allowance money and you go to your piggy bank to pay them back.
The people who worked at the exchequer of pleas were like the King's special helpers. They would count all the money in the piggy bank and make sure nobody was stealing any coins. They would also make sure that everyone who owed the King money paid him back on time.
Overall, the exchequer of pleas was a very important place where the King's money was kept safe and managed well by his trusted helpers.