Jumbo loans are mortgages over the conforming/conventional loans limits of $453,100 ($679,650 in high cost areas). These loans are great to get you more house but often come with more strict credit requirements.
In most cases, you will need a high credit score an a low amount of debt compared to the income you make. Most times you will need to show a healthy amount of money in the bank as well. If you are considering a Jumbo mortgage, you will need to but good amount of money down as well, most times 20% or more.