If someone notifies you of their Google Calendar and you want to meet with them, check their availability. Without looking at his calendar, you can see the suggested hours to "log in" to Google Calendar online.
Check availability in Google Calendar Online
If you use Google Calendar on a Windows 10 or Mac computer, you can check availability for your visitor. Go to the Google Calendar website and sign in to the Google Account you want to use.
On the left, click in the "Search for People" box and start entering your visitor's name or email address. Select them from the list and they will appear in the box.
Click "Create" in the upper left corner to set up your event with this visitor. Enter the desired date and time at the top. Then you have two ways to find a good time to meet.
First, you can click "Find a Time" to view the visitor's calendar, along with your own, for the date and time you selected.
Second, you can click "Suggested Times" in the visitor area of the event details screen. This displays a drop-down list of the hours the visitor is available. You can select an option and the time of the event will be adjusted to this time.
You can also view Suggested Times for guests in full view of an event details page. You will also receive a drop-down list and you can select an hour from the list.
Select an hour and click "Save" at the top, or continue to add details or attach a file to the event.
Check availability in Google Calendar on your mobile device
You can also check the availability of someone in the Google Calendar app on iPhone, iPad and Android. Although you can not see the suggested hours as you can online, you can see if the selected person can meet you at the date and time you choose.
Open the Google Calendar app on your device, tap the "+" icon in the lower right corner, then tap "Event".
Enter the date and time at the top, then click "Add People". Search for or select the person you want to add and press "Done".
Return to the event details screen, click "View Schedules" in the guest section. Then you will see a view of this date and time in the calendar, in colors that suit you and your visitor.
When you set the date and time, click "Save," or keep adding details to your event.
If you can check the availability of someone in Google Calendar before scheduling your event, this will save a lot of time for both of you.
Source of information: howtogeek.com