My 1099 R has code T in box 7. Because I migrated to a new Roth IRA account in 2023. In fact, I started contributing to my Roth IRA in 2010. What should I do in tax rtn?

I have distributed $7000 from my Roth account in 2024. The company helped preparing this 1099 R insisted the code T is accurate. And, they suggested me to file form 8606. I have checked the instruction for line 19 (part III). But I don’t really know how to fill the box on line 19? And, what else I should do? Please help. Thanks.