https://i0.wp.com/shardsofimaginatio...no_monk_60.jpg
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That looks like Battlestance i believe? I don't play monk so i'm unsure but you can unlock it simply through the msq level 60 line Causes and Costs. The Battle stance emote is different for every job.
Kukajoo is right. That's part of the MNK /bstance.
You will eventually and unmissably unlock /battlestance (/bstance) and /victorypose (/vpose) if you progress the MSQ into the Lv60 quests. The animation differs by job.