Back in the days of the UDK or Unreal Engine 3, the units of measurement were based on what was called Unreal Units (uu), where one uu equaled 0.75 in, or 16 units equaled 1 ft. In Unreal Engine 4, the measurement has changed to where 1 uu is equal to 1 cm by default, but the engine allows you to change the conversion ratio between an Unreal Unit and a meter in its World settings, as shown in the following screenshot:

The value of 100.0 in this property equates an Unreal Unit to 1 cm. For example, by changing the World to Meters property to the value of 1 (as shown before), it will equate 1 uu to 1 m and a value of 1,000 will result in 1 uu equaling 1 mm. For the purposes of this project, we will leave the default value of 100 so that an Unreal Unit will equal 1 cm, but for future reference, this is the World settings property you would want to alter in order to change this conversion ratio.