Can You Get Out of a Vague Contract That Says You Have to Pay to Replace Yourself

My question involves labor and employment law for the state of: Maryland

Is there a legal limit to what can be agreed on in a contract?

In my own words, the contract states that if the teacher quits early, the teacher is required to pay the school the cost of replacing them with a new teacher.

Are signed contracts binding no matter how vague they are? Is there an amount of money that it would be illegal for the employer to claim they need to replace the teacher? Is there a legal way to get out of a contract that you’ve signed?

Can You Get Out of a Vague Contract That Says You Have to Pay to Replace Yourself