This is the group of people who can potentially see your ads. You help influence this by adjusting age, gender, location, detailed targeting (interests and behaviors), custom audiences, and more.
Broad Targeting
In most cases, mention of Broad Targeting refers to the removal of all potential targeting filters: No custom audiences, lookalike audiences, or detailed targeting. Instead, rely only on location and letting the algorithm do the work.
Catalog Custom Audiences
If you utilize a product catalog, you can create audiences of people based on their engagement with your products that can be used for targeting and exclusions in your ad set.
Customer List Custom Audience

A customer list custom audience is created by uploading a customer list that Facebook matches with users so you can target them with ads.
Event Custom Audience

You can create an Event custom audience to target those who have engaged with your Facebook event with an ad.