Currency used in Stream is called Kyybucks. It has no direct real value. It is used in the chat for various things, mainly buying Jackpot raffle tickets when the Jackpot is triggered.
Now you can also use them to get 10% discount for coaching packages when you use 1K Kyybucks! More information at Coaching Prices.
How to get them?
You will earn Kyybucks by watching the stream and being active in the chat. You will also get them with subscriptions and donations.
You can also participate in chat games, like fighting the Bosses or going to Casino.
To view your current Kyybucks balance, type !money in the chat.