If you have a credit card or line of credit, the minimum payment is the smallest amount you have to pay every month to keep the bank or credit card company from hounding you... and fining you.
Usually, the minimum payment is just slightly more than the interest you owe on your account, which means it's small. That's a good thing because you might be able to afford it. It's a bad thing because making only the minimum payment will mean it takes you years and years to pay off what you owe (all while you pay huge amounts in interest).