This means Google Ads advertisers can group and report on campaigns based on business category and/or marketing strategy.
For Google Ads advertisers managing large accounts, this new update should simplify reporting efforts and campaign naming systems. It is worth noting however that custom dimensions in Google Ads are entirely different to those used within Google Analytics, as they allow you to report on categories and subcategories based around your marketing strategy and overall business goals.
As promising and beneficial as this new update appears to be it is only in beta and its availability appears to be somewhat limited. If you’d like to double check whether you have access to it, take a look in the “Tools” dropdown menu within your account.