In some directory styles there is a text length counter, that shows an estimation for every listed text about how much of the vertical space would take. The result is related to a "default" column, in other words, the most frequently used one.
Note
Since the GN4 version 2.4, the measurement units in UI are inherited from the default measurement. See Use default measurement in UI.
In the versions prior to 2.4, the calculation and the measurement unit were hard-coded in the configuration file, thus, in your system it may require a modification of the configuration.
See also
Column style for length in various measurement units