Object variables are based on models. Under Elements, you have two types of models that we distinguish as Catalog Models and Models. If you do not have a model to base your object variable on, you cannot make an object variable. Most often an Object variable is based on a Model. These models are designed to have variables that are likely to be used again and again in multiple templates (e.g. first and last names, addresses, phone numbers.) You will learn more about Objects and Models here.
Currently, the only option for an object model is the Appearance in Default Layout Style, and there is only one option under that: popup. When a user is filling in information, a pop-up box will ask all the questions for that Object based on the template needs. The image below shows what that looks like.