Hi Nayoon,
Welcome to Box Community and glad to help!
Looks like you're looking to customize your shared link URL.
When you create a shared link, you can customize its ending. This feature is intended to make content readily accessible to large groups of users, externally or internally, using a customized URL that is easy to remember.
The custom ending to the link must be between twelve and thirty characters, and can use letters, numbers, and hyphens.
Custom URLs are only available to Business and Enterprise accounts.