In contract law in the United States, this is a "liquidated damages" clause. It provides that when one side breaches the contract, it has to pay a certain amount of money to make up for it. Normally this is done where it is difficult to calculate the actual damages in the event of a breach, or where the parties would rather avoid calculating the actual damages--a common example is where you put in an earnest money deposit on a house and then forfeit the earnest money if you do not buy.
However, there are restrictions on what kind of damages are permitted. Notably, a "penalty" usually refers to an unreasonable amount that is unenforceable as against public policy. It would ordinarily be unreasonable to make someone pay a hundred million dollar penalty for breaking a ten thousand dollar contract, for example. Liquidated damages clauses frequently say "this is not a penalty" and "the parties agree this is reasonable" to make it harder to invalidate them on public policy grounds.
Instead, if the liquidated damage payment is a payment meant to reflect actual damages that are just hard to calculate, it is much more likely to be enforceable. You would need to research liquidated damages and penalties in the state whose law governs the contract to determine whether the particular clause is permissible under state law.