The custom ad campaign is used to track the URLs of your website using the unique UTM parameters that are sent to your Google Analytics account. UTM parameters are just tags that you add to a URL to track in your Google Analytics account.
How to create custom ad campaign UTM parameters
Just go to Google URL builder form page.
Website URL: Tracking URL
Campaign Source: Source of this ad campaign.
Campaign Medium:medium of your ad campaign example:email or website or any other.
Campaign Term: Type keywords for this ad campaign.
Campaign Content:differentiate your ad campaign links that point to the same URL.
Campaign Name: Name your ad campaign
For the sample please check the below image.
How to View Custom ad Campaigns in Google Analytics
Login to your Google Analytics dashboard and select your site. Then go to Acquisition -> Campaigns -> All Campaigns. Here you will have a list of all of the campaigns you have been tracking. Just click on each campaign to view and get more information.