@emelie
To determine if a visitor is from a Google AdWords click, you can set up tracking with a UTM parameter in your destination URL. UTM parameters are tags that you can add to a URL to track different elements of your campaign.
Here's how to do it:
Your destination URL should look something like this: https://www.example.com/?utm_source=google&utm_medium=cpc&utm_campaign=my_campaign_name&utm_term=my_keyword&utm_content=my_ad_id
In your custom report, add the "Source" and "Medium" dimensions and filter by "google/cpc" to see AdWords clicks specifically.
With this set up, when a visitor clicks on your AdWords ad and lands on your website, you'll be able to see in your Google Analytics data that they came from a Google AdWords click.