line 5a pensions and annuities

The amount on Line 5a on your form 1040 is what you entered from the Form 1099-R box 1. 

The taxable amount on Line 5b is what you entered from the Form 1099-R Line 2a or it is the amount based on your answers to the follow-up questions if the Line 2a is blank (empty) on your Form 1099-R.

TurboTax summarizes the information on its Form 1099-R Summary, one of the pages available in forms mode of the desktop version or in the pdf of all forms and worksheets obtainable from all versions of TurboTax.

And 1040 lines 4 & 5 are determined by the 1099R if the little IRA/SEP/SIMPLE box is checked between boxes 7&8.  If that box is checked the 1099R goes on line 4a & b.  If that checkbox is missing or not checked it goes on line 5.