It's not a coin but it will determine how much you will have at the end of the bounty campaign. The more stakes you get the more share you will have. Your total stakes at the end of the bounty will be divided by the summation of stakes of all bounty participants then multiply by bounty tokens allocated in that campaign.
Oh that's how it works, thanks for sharing your knowledge about this, I as a newbie have no idea of what is stake, it is based on your profit in a week right? when you are participating in a campaign.