You would enter the amount of property tax that you paid for a second home if you have one. If you don't have a second home, leave it blank. Don't enter property taxes that you paid for a rental property because that information goes on a Schedule E.
There's a cap on the total amount of taxes (state and local income taxes, personal property taxes, and real estate taxes) of $10,000 ($5,000) if you are filing Married Filing Separately (MFS).
For more information, refer to the TurboTax article Claiming Property Taxes on Your Tax Return.