Do you get SSI - Supplemental Security Income - or do you get Social Security benefits? They are both paid by the Social Security Administration, but they are not the same thing. SSI is not taxable. You do not enter it in your tax return. If you get Social Security benefits you should have received a Form SSA-1099. You enter the amount from box 5 of the SSA-1099 form in box 5 in TurboTax.

If you get Social Security benefits but you don't have your SSA-1099 you can get a replacement from the Social Security Administration. See the following FAQ on the Social Security web site for details.

How can I get a form SSA-1099/1042S, Social Security Benefit Statement?

SSI = Supplemental Security Income, which is not reported on your tax return.

But if you received regular Social Security or SSDI, you should have received a form SSA-1099.  That goes in Federal > Wages and Income > Retirement > Social Security