To use your MacBook Air, you need these two accessories, included in the box:
USB-C Charge Cable (2 m): To charge your MacBook Air, connect one end of the USB-C Charge Cable to any Thunderbolt port on your MacBook Air and the other end to the USB-C Power Adapter.
30W USB-C Power Adapter: After the power adapter is connected, fully extend the electrical prongs on the AC plug, and plug the adapter into an AC power outlet.
Other adapters and accessories are sold separately. Visit apple.com, your local Apple Store, or other resellers for more information and availability. Review the documentation or check with the manufacturer to make sure you choose the right product.