Concepts
Everything you build in VX (post types, taxonomies and fieldsets) is configuration. By default it lives in the database, like any setting made in the dashboard. Config as code lets you keep some or all of it in files instead: JSON files or PHP code in your theme or plugin, committed to version control and deployed with the rest of your code.
That gives you reviewable changes, identical models on local, staging and production, and a production site that can't drift from what's in the repository.
Start with How config as code works. If you just want to move a model between two sites once, Import and export is simpler.