Stools are objects from The Legend of Zelda: Skyward Sword. They are small pieces of furniture found commonly in dwellings throughout both The Sky and The Surface. Stools can be used to replenish Link's Heart Containers when sat upon. Along with stools, tree stumps that appear all over the overworld seem to have the same purpose; they both provide Link a place to sit down and replenish lost Heart Containers and quickly regain lost stamina. They are both useful while in Hero Mode because of the absence of Heart Flowers and the fact that downed enemies no longer generate hearts until Link acquirers the Heart Medal.
If Link sits on a stool close to another character, they will more often than not converse with him. For example, Tubert of Thrill Digger will allow Link to ask him questions, and Pipit's mother Mallara will encourage Link to rest and relax as she often does.