Kind is an adjective and kindness is a noun!

Kind is a noun or a adjective, kindness is a noun. Kind when it's a noun mean a group of people or things that belong together or have some shared quality : a particular type or variety of person or thing For example: In this city, you'll find many kinds of people. Kind when it's a adjective mean having or showing a gentle nature and a desire to help others : wanting and liking to do good things and to bring happiness to others. For example: She is a kind woman. Kindness : the quality or state of being kind. (mean like the word "kind" when it's a adjective) For example: We thanked her for her many kindnesses. p/s: I am not sure about my answer, wait for a native speaker or a teacher.