A kusenaoshi is stand for bamboo matcha whisks.
The bamboo whisk (chasen) you use for your matcha tea can be expensive. Using a stand helps extends the life of the whisk and also helps the whisk keep the original shape.
The stand also looks great and gives you a place to store your whisk.
It is safer to store your whisk on a kusenaoshi.
Do not keep it in the plastic case it came to you in. Those cases trap moisture and can lead to mold.
The stands can be found easily online and come in many colors.