First, we need to clarify that there are two different concepts in Tribe: Reputation Score and Virtual Currency.
"Reputation score" is not transferable and the only way to gain reputation points is by being active in the community. Activities like posting content, leaving a comment, receiving like on your contents, and etc will add reputation score to your account. The number of scores you receive for each activity is defined by the admin of the community in the community settings104.
"Virtual currency" is the reward you get on your account. This is transferable and exchangeable. There are different ways to receive virtual currency: by answering the questions which have rewards, or you will receive it manually from the admin216 of the community.
Admins are able to define different options for redeeming the virtual currency by enabling the "Store" option from Admin Panel > Virtual Currency App from the App Settings section> Enable Store> Add Email who receives the redeem request> Add Redeem Options as displayed in the pre-filled example> Save.
Once a user clicks on one of those redeem options, admin will receive an email that user X requested to redeem Y amount of virtual currency as Z gift option. Once the email is sent to admin, the Y amount will be removed from the user's account. The rest of the process will be done by admin manually.
Here's a video giving you an overview of Virtual Currency-