The Flurry Rush is an attack from Breath of the Wild.
Breath of the Wild
A Flurry Rush can be performed immediately after executing a Perfect Dodge. Right when the enemy is about to attack, if Link dodges to the side, or does a back flip at the precise time, he will perform a Perfect Dodge. This will slow time down, at which if Link has a weapon equipped, he can press (Y) to perform the Flurry Rush. This will cause Link to dash close to the enemy where he can perform a number of rapid attacks in a short period of time.
While performing a flurry rush, despite everything moving in slow motion, Link is still vulnerable. If there are other enemies nearby and they attack Link, he will take damage, ending the flurry rush. Link is also vulnerable when attacking enemies that can perform explosive attacks (like Lynels), as he can still get caught on the blast radius.
The amount of strikes in a flurry rush depends on the type of weapon used. One-handed weapons will make 7 strikes, two-handed weapons will make 4, and spears will make 7 to 10. All strikes count as normal strikes and affect the weapon's durability.
The Flurry Rush, in spite of being a special move, does not deplete the Stamina Wheel.