If you have a lot of moolah, you're rich — you have plenty of cash. Moolah is a slang term that means "money."
When you don't have enough moolah to buy a car, you may have to work and save for a while before you've got the moolah to buy it. This informal word is similar to bread or dough, or clams, just a few of the many slang words meaning "money." Experts know this word was coined in the United States around 1920, but beyond that its origin is a mystery.