Source: Xanathar's Guide to Everything

Prerequisite: Dwarf or a Small race

You are uncommonly nimble for your race. You gain the following benefits:

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

• Increase your walking speed by 5 feet.

• You gain proficiency in the Acrobatics or Athletics skill (your choice).

• You have advantage on any Strength (Athletics) or Dexterity (Acrobatics) check you make to escape from being grappled.