Depends on whether it's the taxpayer's main home or a business property.

If it's the main home, then 8979 with F checked

If it's a business property (rental, investment, etc.), then 4797.

If you're asking where to enter it in ProSeries, click that awesome green "Where do I enter" button and type "1099-S." It should take you straight there.

Happy filing 🙂