Trait Sets are an optional feature, that allow you to separate groups of Traits to be mixed together when your NFTs are generated.
If, for example, you are generating a PFP project, and you have two different characters being released in the same Drop, you might use trait sets to separate the Traits of each of the individual characters.
Trait Sets properties are defined below:
Name: an internal-only name to help refer to this trait set
Supply: the number of items in your drop that should be generated from this set. This must be less than or equal to your total Drop supply,
Metadata Title / Metadata Value: up to 2 optional metadata properties you can define that will be added to every NFT generated as part of this set.