A charger is not included in the scope of delivery. Only a USB cable is supplied for charging and updating. The battery is charged in the Osmo Mobile itself via USB, for example on a PC or via a USB adapter (e.g. from a smartphone - 5V 2A 10W).
However, you can also buy the charging station (I recommend buying a second battery anyway) to charge the battery externally:
Dji Osmo Battery Charger