It's used as a medium for trading. Instead of trading a cow for 10 chickens, you trade a cow for paper which could get 10 chickens. But with that medium, you don't have to get the chickens if you don't want to. You can use it for butter, milk, eggs.
That is what money is for.
You can trade your services for a house and food, but instead of the actual house, you get paper which can get you that house. So you can get whatever house you want that you can afford. Or what your services are worth. People who offer valuable services get more paper. People with services which are not so valuable get less paper which means less food less house less clothes.