Balloon mortgages are short-term loans that begin with a series of fixed payments and end with a final, lump-sum payment. That one-time payment is called a balloon payment because it's often at least twice as much as the previous ones, leaving many borrowers with a final bill for tens of thousands of dollars (or more).
In some cases, you may be able to negotiate with your finance provider to spread the balloon payment over monthly instalments – this is essentially what refinancing is. Doing this can help make the payment more manageable and reduce the financial strain of a large lump sum payment.
If there is a "balloon payment" (final balance), enter it into B4 as a positive value, and use the formula =PMT(B2, B3, -B1, B4). Those formulas also assume that payments are at the end of the period (i.e. end of month). That is typical. However, for car leases and such, the payment is at the beginning of the period.
The traditional mortgage is only for stationary property. It's suited for long-term real estate investments. Chattel loans are for property that can be easily moved. They're also an option for borrowers who want their loans approved faster and with shorter repayment times.