With this currency, players can purchase new melee weapons, firearms and combos, upgrade their current weapons, increase health, attack and defense, and gain new special attacks. (glitchcat.com)
But then, that's all things we've had since the original — all Splatoon 2 actually adds are new Special attacks for all of your loadouts, some new weaponry, and some new maps. (wccftech.com)
You also unlock new special attacks which use up some stamina or rage depending on the attack. (gamergeddon.com)