Stance of the Sturdy Ox is a monk stance learned at level 10 for those with the Brewmaster specialization. It is a tanking stance and provides a host of benefits, including the ability to stagger damage.
Staggering damage is unique to Brewmaster monks, allowing them to avoid taking a full, possibly lethal, amount of damage all at once. Instead, they take 80% of the damage up front, then the remaining 20% is applied over 10 seconds. This makes it much easier for healers to keep the monk alive, as well as allowing time for the monk to use [Purifying Brew] if high enough level.
Patch 6.2.0 (23-Jun-2015): Stance of the Sturdy Ox now increases armor by 125% (up from 75%) and provides a 20% base Stagger percentage. Additionally, the Stagger effect no longer works against attacks which ignore armor.
Patch 6.0.2 (14-October-2014): Stance of the Sturdy Ox now also reduces the chance for attacks to be parried by 3%.; Stance of the Sturdy Ox now replaces Stance of the Fierce Tiger for Brewmaster Monks.; Stance of the Sturdy Ox now reduces the global cooldown of the Mistweaver Monk’s abilities by 0.5 seconds.; Stance of the Sturdy Ox now increases Stamina by 25% (up from 20%), reduces magic damage taken by 10% (down from all damage taken by 25%), and grants a 50% increase to Armor, but no longer increases Energy regeneration.