New York Resident Deductions / Self-Employment Tax
To get to this screen, you had just gone through a bunch of screens asking you to allocate your 2017 income to New York versus not-New York because I assume that you are a part-year resident (if you are filing something else, let me know).
Now, TurboTax has discovered one federal deduction - your self-employment tax - that it needs to allocate between New York and not-New York.
Earlier, did you allocate your self-employed business income between New York and not-New York? If so, use the same New York percentage as you used there to multiply the federal self-employment deduction and get the New York Resident deduction.
Basically, just as you allocated business income to New York and not-New York, you will allocate deductions derived from business (which your self-employment tax definitely is) the same way.