優しい (yasashii) means "kind," "gentle," or "tender." You use it to describe a person's character as compassionate and considerate, or an action that is mild and not harsh. It often relates to how someone treats others. For example, 「彼女はとても優しい人です。」 (She is a very kind person.)

性格が親切で思いやりがあることや、態度が穏やかなことを表します。「彼女はとても優しい人です。」