You can redeem it on the Garena website, which is located at reward.ff.garena.com/id. Here are the steps:

1. Visit the Garena website.
2. Login using your Facebook, VK, or Huawei account.
3. Enter the FF redeem code & tap Confirm.
4. If successful, the prize item will appear in the In-game Mail (Gold and Diamond will be added automatically).

There are two things that must be considered in exchanging the FF redeem code on the Garena website.

First, the FF redeem code has an expiration date. This means that expired code cannot be used. Second, the FF redeem code cannot be exchanged using a guest account. Please bind account to Facebook or VK to receive rewards.