format-list unpivotizes the output of an object. That is, the object's property values are printed each on a separate line rather than all being displayed in the same row.
For example, the default output of get-process looks like so:
However, if it is pipelined to format-list, it becmoes:
PS C:\> get-process PowerShell | format-list
Id : 7148
Handles : 760
CPU : 77.75
SI : 1
Name : powershell
Id : 28700
Handles : 732
CPU : 2.546875
SI : 1
Name : powershell