This regional plan covers multiple countries on a single eSIM, so you don't need to buy a separate plan for each destination on a multi-country trip. The exact country list for each plan is shown when you tap "Coverage" on the plan detail page.
Activation works the same as a country plan: scan the QR code from the confirmation email, and the validity timer starts only when your phone first connects to a network in one of the covered countries. The eSIM seamlessly switches between local partner networks as you cross borders.
Which plan to choose: Regional plans typically use 4G/LTE on partner networks (5G in most major cities where supported). For long trips that stay primarily in one country, a country-specific plan is usually cheaper; for trips that cross 3+ countries, the regional plan is more economical.