A very well known add-on in the Blender community that aims to enhance your hard surface modeling workflow. It includes a large collection of tools and macros with the aim to speed up your modeling workflow.
Hardops introduces its own terminology and a lot of different systems to enhance and work along the existing tools in Blender.
A good place to start is the manuals getting started pages that will guide you through the different places you will find hardops in the user interface.
From there dive deeper into the main tools and sharpening, beveling and dicing. Then move on to the "systems". Just know that you will need to take your time if you want to grasp this add-on in full.
It has quite the learning curve but once you get into it and start to use it regularly you will find that it holds what it promises. Just keep in mind that this add-on is on the more advanced spectrum of Blender add-ons that are out there.
HardOps comes either stand alone or bundled with BoxCutter. A tool to speed up and enhance boolean functionality.