"Deduction" on the HSA Summary screen refers to the amount of contributions that you made to your HSA outside of your employer (i.s., not through the payroll deduction scheme).
This amount will be deducted from your taxable income, appearing on line 12 of Schedule 1 (1040) (for 2019).
"Tax-free employer contributions" refers to the sum of the amount that your employer contributed to your HSA and what you contributed to the HSA through a payroll deduction scheme. This amount is normally the amount on your W-2 in box 12 with a code of "W".
This amount was never included in your wages so it does not appear on the 1040 (but does appear on form 8889).
"Deduction" and "Tax-free employer contributions" added together is normally the total amount contributed to your HSA during the year.
[Edited 3/24/2020 1:21 pm CDT - updated line reference for 2019]
