The properties of an object in Roblox describe how that object looks and behaves. For example, a Part has properties such as Position, Material, and Size which determine where the Part is and how it appears. After clicking a part, the Properties window will show all of the properties of that part. Any changes you can make with a tool, such as the tools described in Creating a new game, can be made by manipulating the values inside the Properties window. You will also see properties in this window that don't have a Studio tool.
To open the Properties window, click on the View tab and then click the Properties button. To see the properties of an object, click on it in either the 3D view or the Explorer.