What regional code means

Jetson developer kits have dedicated regional codes.
for example, 945-82972-0040-000 is for US, CA, JP, TW, PH areas.

Would you explain what the regional code means?

These are ISO 3166-1 alpha-2 codes indicating where the product can be purchased/imported/used. All regulatory and compliance requirements have been met to offer the product to the indicated places.

One practical implication: developer kits including a power supply will include the appropriate plug (or plugs).