That is on a 1099R. The easiest way to get to the 1099-R entry screen is to simply search for 1099-R (upper- or lower-case, with or without the dash) in your TurboTax program and then click the "Jump to" link in the search results.
Enter a 1099R under
Federal Taxes Tab or Personal (Home & Business)
Wages & Income at the top
Then scroll way down to Retirement Plans and Social Security,
Then IRA, 401(k), Pension Plans (1099R) - click Start or Revisit
There are 4 boxes. Be sure to pick the right box for the kind of 1099R you got.
If you are filing a Joint return be sure to pick which person it is for.