A target takes the beast's statistics except for alignment, Intelligence, Wisdom, and Charisma. It also gains the hit points of the beast and is at the maximum health for said beast. While in this form, the target can't speak or cast spells and can only do the actions that the beast could.
If a target hits 0 hit points, it reverts to its normal form and resumes the number of hit points it had before transforming. If there is excess damage, it deducts from the target's resumed hit points. However, as long as its normal form isn't reduced to 0 hit points, it isn't knocked unconscious.