*full disclosure. Not CPA nor a tax preparer*
Probably don't owe taxes. The lifetime exemption amount is $11.7M for a single person and double that being $23.4M for a married couple. Since in this examples "parents" made the gift then I assume they're a married couple. If the married couple never gifted more than the annual gift exclusion before ($15k in 2021, but varies by year) then they should still have $23.4M of lifetime exemption.
1) Meaning if that gifted money was not over $23.4M then there will be no gift taxes to pay. The purpose of this form will then be for the IRS to just track how much left of the $23.4M they have. For example, if they gifted you $3.4M to purchase the house then they have $20M left of lifetime exemption.
2) If they did gift you over $23.4M, let's say $24.4M as an example. They will owe $2.64M in Gift Tax (($24.4M Gift - $23.4M Lifetime Exemption left as of Gift Date) x 40% Tax Rate).
