Source: Player's Handbook

Accustomed to the rough-and-tumble fighting using whatever weapons happen to be at hand, you gain the following benefits:

• Increase your Strength or Consititution score by 1, to a maximum of 20.

• You are proficient with improvised weapons.

• Your unarmed strike uses a d4 for damage.

• When you hit a creature with an unarmed strike or an improvised weapon on your turn, you can use a bonus action to attempt to grapple the target.