Synchronize your Google calendar to you account. You will be able to see your scheduled events in Google calendar within the calendar on your account and schedule with clients at times that you are available.

On your account dashboard click on Settings> Availability & Calendar or if you have staff members enabled on your account, navigate to Settings> Staff> Edit the desired staff member> My schedule 
Under Calendar Sync. section find Google Calendar option and click on Sync Availability.

Login to your Google account and click on Accept to grant the system access to read your free/busy times from your Google calendar.

Once your Google calendar account is connected, you can choose which calendars (other than the default calendar) on your Google account should be synced into the system.
All selected calendars will affect your availability.