The Sales objective is a new goal-oriented way to publish a Meta campaign with catalogs. This objective merges the old Product Catalog Sales objective and Conversions objective.
How to create campaigns with the old objectives (Product Catalog Sales and Conversions)?
If you want to create what was earlier known as Product Catalog Sales, then choose the catalog in the campaign setup. Otherwise, this will automatically be recognised as a Conversions objective.
What new can you do that you couldn't do before?
This objective comes with the new Meta experience and much more comfortable UI/UX.
You can select manual placements with much more visibility on what the outcome will be.
Catalog selection is now moved to the campaign level instead of defining it during setup. Now, you can change your catalog even once you start creating a campaign.
More comfortable carousel creation on ad level.
If you set your catalog on campaign level (analogue of ex Product Catalog Sales), the product set is then configurable on ad set level. The new option brings setting a special product set on ad level which will override the one on the ad set.
To be able to see this option on ad level, you should select "All Products" on ad set level.
This objective keeps up with new Meta naming conventions, including the Advantage features.
Better support for static creative - Multiple variants for copies and standard enhancements
What will happen with the ongoing campaigns with the old objectives?
Nothing. Meta still supports ongoing campaigns with old objectives, you just cannot create a new one.