To create a presentation using a Zap, you will first need to create a template presentation to bring your data into on your Google Slides account.
So first head over to your Google Slides account and make a new presentation from a template or from scratch.
You can read more on how to create a Google Slide presentation here
On your template slide, you can specify what fields you want to add to your slide from your Zap by entering a word surrounded by two braces (curly brackets) as placeholder variables. Like this:
Tip: you can add placeholder variables across multiple slides on one presentation.
Then, when you are setting up your Zap template using this Action, select your template from the "Template Presentation" drop down and then you will see all the fields you specified with braces like this:
Tip: to pass images onto the template, you just need to create a text placeholder variable on your presentation template, then pass on a URL to a hosted image on your Zap template.
Then, each time your Zap runs, it will create a new present based on your template!