You will need to have $JET in your wallet if you want to sell $JST token. $JET will be burned when you sell $JST tokens. The ratio is 10000:1. This means if you sell 1 BNB worth of $JST, 10000 $JET or $JET V2 in your wallet will be burned.
You can earn $JET reward automatically through buying $JST or you can stake to earn $JET V2 after JUMPN farm release. If you swapped 1 BNB for the $JST token, you would earn a random amount of $JET token from the range of 0 to 20000 $JET.
JAC can also be used to accelerate the transaction of Jump Satoshi Token. The ratio is 1000:1 For each 1 BNB swap from JST, you will only need to burn 1000 JAC in your wallet.