Actions with the flourish trait are special techniques that require too much exertion for you to perform frequently. You can use only one action with the flourish trait per round.
Ranger
This indicates abilities from the ranger class.
Source: Player Core pg. 157
Requirements: You are wielding two melee weapons, each in a different hand
You swiftly attack your hunted prey with each of your weapons, potentially combining their damage into a single devastating attack. Make two Strikes against your hunted prey, one with each of the required weapons. If both hit the same hunted prey, combine their damage for the purpose of its resistances and weaknesses. Apply your multiple attack penalty to each Strike normally