Official Gmail Blog: Save time with smart scheduling in Google Calendar
Powered by Google’s machine intelligence, “Find a time” suggests meeting times and available rooms based on your preferences, which saves you lots of time and gets everyone together faster. Time and room suggestions are smart, too: They don’t just identify the first free slot in a grid, they also locate the next best slots as a back-up. For example, when Calendar doesn’t find availability for your preferred time, it then looks for conflicts across the group that are easier to resolve, such as recurring 1:1 meetings. And although “Find a time” makes smart suggestions, you're always in control — just tap the grid to pick a time that's a better fit.