Heads Up Display
The Equipment panel displays all of the addon modules currently installed on your ship, as well as any cargo you're carrying.
Cargo crates that you pick up mid-flight will be automatically be displayed here, and the icon will give you some idea of what type of item it is. Carrying cargo can add a lot of mass to your ship. You can jettison all of your cargo by pressing the jettison key (default: "j"). This can significantly lighten your ship's load, making combat easier.
You will also see a listing of all your weapons, and some information about their states. If the weapon has limited ammunition, a number representing how much ammo is left is displayed to the right of the icon. Weapons that are currently selected have a cyan border around their icons. (By default, all weapons are assigned to either a primary or secondary fire group, but you can configure this to your liking when docked with a station.)
The equipment panel will resize if you're carrying a lot of cargo, however, you can save space on your HUD by minimizing it (default: "o").