Ann: Leads investment into Sky Mavis, maker of Axie Infinity, page-265

Axs is definitely used in game play. You need axs to breed Axies, believe it starts at 4 for first time breeding and goes up (so minimum for first breed is around $160usd cost).

The general idea behind Axie is to try and be a self regulating economy. You need to burn both SLP and AXS to breed whilst generating SLP daily through quests. Not sure of the generation of AXS though.