Your credit history is your history of paying your bills on time (or not) and repaying what you owe.
If you have a strong credit history, it means that you've been paying what you owe on time and in full. The length of your credit history matters, too. The longer you stay with companies and keep paying them back, the better your credit score. If you're just starting out in life and haven't been paying bills for very long or have only had your credit card for month, you may not have enough of a credit history. That can make it harder for you to get loans.