Form 8889: Health Savings Account (HSA) is used to report HSA contributions, distributions, and withdrawals.
We'll automatically fill out Form 8889 if you and/or your employer contributed to an HSA (usually indicated by code W in box 12 of the W-2), if you used funds in your HSA (reported on Form 1099-SA), or if you inherited an HSA.
Tip: On jointly-filed returns, Form 8889 will have a -T or -S suffix, for example Form 8889-T or 8889-S. This simply denotes who the 8889 belongs to (T for taxpayer, S for spouse).
Here is the direct link to the IRS form 8889 for a paper form or for review: https://www.irs.gov/forms-pubs/about-form-8889
What do you mean by Box 12? 12a, 12b, 12c, or 12d?
In my case, I have D in 12a and DD in 12b.
Since you do not have a code W in box 12 then you made no contributions to the HSA so did you take a distribution from the HSA account in 2019? If so they would have sent you a form 1099-SA and if you enter that in the program the form 8889 will automatically be produced.