Source: Player's Handbook

You have martial training that allows you to perform special combat maneuvers. You gain the following benefits.

• You learn two maneuvers of your choice from among those available to the Battle Master archetype in the fighter class. If a maneuver you use requires your target to make a saving throw to resist the maneuver's effects, the saving throw DC equals 8 + your proficiency bonus + your Strength or Dexterity modifier (your choice).

• You gain one superiority die, which is a d6 (this die is added to any superiority dice you have from another source). This die is used to fuel your maneuvers. A superiority die is expended when you use it. You regain your expended superiority dice when you finish a short or long rest.