The variable editor is accessible by the UI – Data switch in the middle of the view canvas toolbar.
On the left, you can choose between different variable types:
Every variable has schema, which defines its structure: is it a text string, a number, a boolean value, or something more complex like an array of objects.
The scheme editor lets you change the key and type of existing properties. For objects, you can also add and remove individual keys.
Data variables differ slightly from the other variable types in that their schema is defined in the data configurator (accessible via the Data section of the global toolbar).
Under the hood, a data variable is in its essence just a page variable that has a specific schema.
However, when you add a One or All type data variable, logic is included that fetches the data from the backend and populates the variable. New type data variables are simply initialized as empty objects, so you can e.g. bind your form fields to such a variable.
Translation variables allow you to easily define multiple translations for text values.