LMI stands for Lender’s Mortgage Insurance. This protects the bank in case you default on your home loan. This is an additional charge, typically if your deposit is less than 20% of the purchase price.
If you want to buy a property for $500,000 and have $50,000 (10%) saved for a deposit, the bank may charge you LMI. LMI is a once-off payment, and can often be added to your loan amount.