Nominal money is the amount of money you have. Real money is the value of that money.
If Alice had $50 in her purse in January 1970 and Bob had $50 in his wallet in January 2020, they both have the same nominal amount of money. Due to inflation, however, Alice's $50 is worth much more than Bob's $50. If you wanted to do a meaningful comparison of how much wealth each had, you'd need to convert nominal money into real money. One way to do that is to look up historical inflation (or use an inflation calculator). That shows that Alice's nominal $50 was worth a real $548.87. That is, Alice could get almost 11 times more goods and services for her money than Bob could get for his.
From a personal finance perspective, if you're putting money in a savings account that earns 0.5% interest while inflation is averaging 2%, the amount of money you have in nominal terms is increasing at 0.5% per year. But the amount of real money you have is decreasing at a rate of 1.5% per year since you're not making enough to keep up with inflation.