Generally, if you have to ask, it's because you missed a selection while working through the SCH E section. Either that, or you're just not done and haven't got to yet another section yet.
In the Property Profile section there are three selections that you must make.
- 2020 is the first year I rented this property (it's okay if you don't have this option to select)
- I rent out a part of my home.
- I converted this property from personal use to a rental in 2020.
Then on a later screen in the property profile section you'll select the option for "Yes, I will enter total amounts and let TurboTax do the math (recommended)". Then you'll be asked for the percentage.
Now for this particular scenario you'll have another issue in the "assets/depreciation" section. But so that I don't risk causing "information overload" lets deal with that separately when you get to it.