It is a code you can give to your friends. Once they sign up using your referral code, you will get a 10% discount (subscription fee) and also a 10% commission (from your friends total subscription fee who used your code) you will receive on your wallet.
You referral code is located on your account settings. Be sure to enter your wallet address to receive the commission.
[caption id="attachment_38" align="alignnone" width="205"] Account Setting[/caption][caption id="attachment_39" align="alignnone" width="300"] Referral Code[/caption]