Answer:
To avoid slipping while playing badminton or to increase friction between the shoes and the badminton court or to enhance the grip.
Explanation:
As the question is general so I will try answer it generally.
As badminton court is usually slippery and flat with no or very little friction and while playing badminton, players have to move very fast from place to place.
So, in order to effectively move faster to take the difficult shots with accuracy badminton players increase the friction between their shoes and the badminton court by shuffling resin to their shoes. It helps to enhance the grip.
