Money is a collective agreement. A $55 bill has no value by itself — it is paper. It is worth something because everyone has agreed that it is, and that agreement is enough for it to work as a medium of exchange.
Before money, people used barter: you would exchange directly what you had for what you needed. The problem was that to buy bread, you would have to find someone who needed exactly what you were offering. Money solved this: it is a universal intermediary that everyone accepts.
💡 Example
If you have a kilo of apples and want milk, with barter you would need to find someone who has milk and wants apples. With money, you could sell your apples to anyone and use that money to buy milk from anyone. Much simpler.