You do not enter the Social Security benefits in the section for a W-2.
You will be receiving a Form SSA-1099 in January for the benefits paid in 2019.
To enter Social Security benefits reported on form SSA-1099
Or enter ssa-1099 in the Search box located in the upper right of the program screen. Click on Jump to ssa-1099
Up to 85% of Social Security Retirement/Disability/Survivors benefits becomes taxable when all your other income plus 1/2 your social security reaches: