Ability to update Metadata from Apex. Simplify your app’s setup and upgrade experience by working with metadata from Apex.

You can retrieve metadata from an org synchronously. Then you can inspect this metadata and update it, and you can also create metadata.

Check the below link for more information

https://developer.salesforce.com/blogs/engineering/2017/05/introducing-apex-metadata-api.html

Trailhead link – https://trailhead.salesforce.com/en/modules/apex_metadata_api