The Units section of the Settings/Configuration... window is used to configure the units used to display various values in the program. There are a large number of units, such as for power, weight, energy, distance climbed or descended, and so on.
Each unit value has a Precision option to dictate how many digits to display after the decimal.
Some units have a Pad checkbox to zero-pad the values.
Units suffixes can also be used in the Query Language, described in another section of this documentation. They will modify the query appropriately, so for example, you can show all tracks more than 50 miles in length even if the displayed unit is kilometers.