Put your earbuds back into the case to recharge, a fully charged case can recharge both earbuds up to 4 times. The LED indicator on the case shows its battery level, from green (full), through orange to red (low).
Connect the case to a USB power source via the included USB-C cable to charge it. When your earbuds are in the case, they turn off. Taking them out will turn them on and try to reconnect.
(5.) Case battery LED indicator.
(6.) USB-C port for charging.