A more thorough explanation:

Definition: Stipulatio aquiliana is a type of contract used in Roman law to settle all the liabilities owed on various grounds by a single contract. It was named after Aquilius Gallus, a Roman jurist from Cicero's time.

Example: Let's say that John owes Mary $100 for a loan, $50 for a broken vase, and $75 for a damaged car. Mary owes John $25 for a book. Instead of making separate contracts for each of these debts, they can use stipulatio aquiliana to settle all the debts at once. They would work out the items and arrive at the balance, which is $200 ($100 + $50 + $75 - $25). This balance being paid or otherwise arranged, each party would then make with the other this stipulatio, which was a comprehensive formula. This would novate all the claims and turn them into a single promise, for an incertum. These mutual stipulations might then be released by acceptilatio.

Explanation: In the example, John and Mary use stipulatio aquiliana to settle all their debts at once. Instead of making separate contracts for each debt, they work out the items and arrive at the balance, which is $200. This balance is paid or otherwise arranged, and each party makes a stipulatio with the other, which novates all the claims and turns them into a single promise. This simplifies their accounts and makes it easier to settle their debts.