Gift points are used to redeem rewards on AetherHub which are mostly redeemable codes for MTG Arena. The Reward section can be found under the Shop menu. You can also exchange Gift Points for NRG Currency, which you can use to buy AetherHub features.
These points are not purchasable, they hold no value other than being able to redeem rewards. They are given to Content Creators, or we use them as rewards for our tournaments or ranking ladder. As of now, there is no automatic way of receiving these points but we are considering some incentives for rewards in our MTGA Assistant extension.
Content creators and users that recieve points can send these to other users by either going to their public profile and clicking the Gift button or sending them via Account -> Edit Profile