Line 13 is the allowed HSA contribution that you made directly to your HSA, outside of your employer. This number would appear on line 25 on Schedule 1 (Form 1040).
This is different from the code W amount in box 12 on your W-2, which is called by the IRS the "employer contribution", even if you contributed part or all of it.
Why the difference? Because you don't receive a "deduction" for HSA contributions made through your employer. Instead, the HSA contributions are excluded from your income, that is, before your W-2 is printed, your employer removed the code W amount from Wages in boxes 1, 3, and 5.
If you have a code W amount of $6,950 on your W-2, then line 13 should be zero, for the reasons I give above.