Two-way synchronization between Bitrix24 and Google Calendars means all events created in Google Calendar are automatically synched with Bitrix24 calendars and vice-versa (
here is how to configure).
If you use Google Calendar on your mobile device, let your phone calendar sync with Bitrix24 (
here is how to connect them). You can schedule events or appointments on your phone, and they will be displayed in Bitrix24 and the other way around.