The Vehicle Inspector should give you a quick overview of your vehicles. What do they / what they have loaded / which are active etc. etc. In Multiplayer and Single Player Games.
How to install FS19 mods?
Firstly find a mod which you like and want to download. Then download a mod to your PC. Mods are usually in .zip format file. But sometimes it can be in .rar. If a mod file is a .zip format no needed additional actions. If a file is in .rar, then you must unarchive mod with software like WinRar or Zip7. Windows 10 users no need to use software for archives, Win10 itself has a feature to unarchive files.
The next step is to find mods folder in your PC. Usually, it is in Documents/My Games/Farming Simulator 19/2019. Open the "mods" folder and put downloaded .zip archive or unarchived .rar file to this folder.
Last step. Enjoy of FS19 mods!
how do you even turn it on?
It turns on automatically at the top left when the help menu is OFF.