I had a HSA account but what does it mean when it says: Form 8889-T: (each month) plan type check box must have a seclection. No entry, Line 3A6, None, Self, or Family

I expect you're on the page of the interview that's mimicking the "Line 3 Limitation Chart and Worksheet" that's on page 4 of the Instructions for Form 8889, or have not completely filled out that particular page in the interview.  It's essentially figuring how much you can contribute to your HSA based on your particular circumstances.

Chart is here <a rel="nofollow" target="_blank" href="https://www.irs.gov/pub/irs-pdf/i8889.pdf">https://www.irs.gov/pub/irs-pdf/i8889.pdf</a>  on page 4

This means that you did not tell TurboTax the type of HDHP coverage you (or, if married filing jointly, the individual who is listed first on the tax return) had for June.  You must select Self, Family or None.  (You must also select None if you were covered by Medicare or other disqualifying coverage for that month.)