In your ad groups, you can select all types of targeting, as well as their combination. In combination, different types of targeting are mutually exclusive, meaning they limit each other.
When targeting men, women or age, the price for each gender or age will be considered preferentially in the auction.
If you are trying to reach new potential customers, it is recommended to exclude the list or lists with existing customers in the Retargeting tab. You can do so at the ad group level, or at the campaign level. If you do so, the campaign will not be displayed to existing customers.
If you select Retargeting and Placement simultaneously as your types of targeting in one ad group, your advertisement is going to be displayed only on the selected websites and only to the users in your retargeting list.
As the example shows, the combination of different types of targeting limits the audiences significantly, even when using only two different types. Therefore, it is recommended to thoroughly consider the effect on your audience when combining various types of targeting.
The exception is the combination of Retargeting and Intents. Intents are considered as a form of retargeting, and therefore these two types of targeting complement each other.