Drawing Dimensioning
This is the FreeCAD Fabrication Drawings creator - a historical method of OSE to extract fab drawings. It's quick and dirty - in FreeCAD 16.
The more advanced version, with a correspondingly higher learning curve - is the TechDraw Workbench above FreeCAD 16. We recommend quick drawings (such as for pasting in build cheatsheets) in Drawing Dimensioning workbench, and more professional (takes longer, has more specific info) ones in TechDraw.
Now that you have the overview - it's your choice which tool to use in which context.