The properties editor is an essential part of the development process. There, you can change almost all properties of the selected object, scene, camera, etc, like:
The screen resolution;
Frames per second;
Name and position of selected object;
Constraints and modifiers;
Materials and textures properties;
Physics properties of selected object;
In this section you have a detailed description about each tab of the Properties editor.
The Render layers and Particles tabs don’t apply to UPBGE, so they won’t be explained here.
This section will explain properties belonging to UPBGE only (Blender Game renderer) or, at most, relevant properties for game development. For other Blender properties, see the official Blender manual.