I don't know if I had a roth for more than 5 yrs before 2019. Why do I need to know that?

The five year question is used to determine if your Roth distribution is a qualified distribution, but it's asked in the Roth section in TurboTax whether you have a Roth distribution or not.

If you don't have a Roth distribution on your tax return, you can just answer to the best of your memory whether you opened your first Roth account in 2014 or earlier. 

If you do have a Roth distribution, you will need to figure out when a Roth account for your benefit was first opened. You can check your records, or call the company that holds your Roth account. 

A qualified distribution is a distribution from your Roth IRA that is made after the 5-year period beginning with the first tax year for which a contribution was made to a Roth IRA set up for your benefit.

In addition, a qualified distribution is:

• Made on or after the date you reach age 59½,
• Made because you are disabled.
• Made to a beneficiary or to your estate after your death, or
• One that meets the requirements listed for a first home purchase (up to a $10,000 lifetime limit).

Thank you so much.

"I don't know if I had a roth for more than 5 yrs before 2019."

That's not what TurboTax is asking.  TurboTax is asking if you simply had a Roth IRA at any time before 2019, no matter how long before 2019.  If you had a Roth IRA before 2019, you will have received a Form 5498 and account statements from the Roth IRA for some year prior to 2019.