Saw a good reply on the STeX EXCHANGE Telegram for this earlier:

The A2A token functions as a utility token. It's comparable to BNB with some nifty tweaks to make it even better, namely A2A Shop is a great incentive to ensure high token prices. Like Ivan said, there'll be an airdrop here. You can also of course take place in the ico, the ico will be AFTER alpha launch of STeX. For a more clear explanation of A2A, watch this video: https://youtu.be/A9O4jQlpiFs